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Oliver
02-08-2011, 06:47 PM
Thanks to JCO, the DIY Aquaponics forum owner, for putting up this area so I could post this series of articles.

This is the first of a series of posts that are going to teach you most of what you would need to know about Aquaponics in order to build and maintain your own system. So, if you're curious about the most amazing food growing technology on the planet today, read this series of educational posts on Aquaponics.

These articles were originally written to address those who are of the belief that we are about to see some serious changes in our economy, along with the price and availability of food. With this in mind, I felt it was time to write this primer to Aquaponics so that those who wish to prepare could have a year round capability for helping to feed themselves and their family.

As these articles progress, I will be talking about family sized systems and focusing on the type that I know best. I realize that there are a number of viable approaches to building Aquaponics systems that many Aquaponic pioneers have experimented with and developed. Due to this emerging technology, there are many differing opinions held by those involved in this wonderful gift of nature. I can only tell you what I believe to be true from all that I have read about other's efforts and from my own experience. Historically speaking, Aquaponics as a technology has been around for a hundreds of years; but ironically, it also is still in its infancy as a family food growing technology. There is still much research to do in this area and much to learn.

These posts are aimed at those who want to build their first system and have the best chance of it working well and producing food.

Oliver

---

What is Aquaponics and why should I care?

Aquaponics is an ancient food growing technology that has been around since the Earth has had water with fish and plants growing together naturally. Aquaponics is nature at work. In nature, the fish eat whatever they find for food, and their waste is broken down by the bacteria in the water creating nutrients for the plants. The plants then absorb these nutrients; and in doing so, they help clean the water for the fish.

The word "aquaponics" comes from two separate words. The first word is "aqua", which, of course, means water; but in this case, the "aqua" is from another compound word "aquaculture" (the raising of fish). The second word is "ponics", which is latin for work, and comes from its use in "hydroponics" (working at growing plants in water, hydro).

So, aquaponics is raising fish and growing plants by using the nutrient rich water provided by the fish.

The reason one should care about aquaponics is that it is a year round food growing technology, which can supply you and your family with fresh veggies and fish regardless of the season. Most fish species take a year or more to grow out to edible size. Because of this long term growth, the system must be placed in an environment that allows for year round operation. In tropical climates, an aquaponics system can work outside with minimum cover. In milder climates, it must be placed in an environmentally controlled green house. In harsh climates, it must be placed indoors with grow lights to replace the sun and grow your plants.

The plants grown in an aquaponic system grow out in less time, grow year round, can be planted more densely, are tastier and require 90% less water than does tillage farming. Also, if the aquaponics system is properly designed, it takes up much less space than does tillage farming. Some plants can be grown directly in the fish tank to absorb the nitrates from the water as any one who owns an aquarium knows. Most aquaponics farmers separate their fish tanks from their plant grow beds allowing them more flexibility in the way they grow and in what they grow. The water is circulated between the fish tank and the grow bed using a pump. This is known as a recirculating aquaculture system that contains two food sources, fish and vegetables. Some grow their fish for food while others keep their fish as pets that also serve a useful purpose, which is fertilizing the plants.

But there is a third living organism in the aquaponics equation, the beneficial bacteria. They are the pro-biotic of the system and live in what is called a bio-filter. Just like the name says, the biology (bacteria) filters the waste in the water, not by removing it, but by converting it into nitrates. It could be called a bio-converter but it is called a bio-filter instead. In an aquarium, where there are only a few fish for the amount of water, the bacteria live in the water, the sand on the aquarium bottom and on any surface where they can attach themselves. In an aquaponics system, the amount of fish per gallon of water is much higher than what is usually found in an aquarium. This higher density requires an additional amount of filtration; therefore, a separate bio-filter becomes part of the recirculating water path in the system.

Before discussing bio-filtration, I want to address the concern some may have for the high density of fish in the system. In a backyard or home aquaponics system, we are talking about one pound of fish for about every six gallons of water maximum at full fish growth. Commercial fish farmers usually run much higher densities, which requires special filtration and oxygenation of the water. Even at six gallons per pound of fish in the system, the fish tend to school together somewhat because it's the nature of fish to create schools. They were introduced into the same tank when the were very small, grew up together and like to hang out with each other. When fish get stressed, you will know it by their unnatural behavior. At these densities, your fish will appear relaxed and healthy. I will be discussing the fish in much more detail in a later segment.

The fish give off two types of waste, which, if allowed to accumulate, is toxic to them. As with any living organism, fish cannot live in their own accumulated waste. The first type of waste is ammonia, which is secreted from the gills and found in the fish urine. The second type is fish waste solids. We refer to this as fish poo.

The required bio-filter is a part of the aquaponics system. In many systems, media filled grow beds double as the bio-filter because they have a large amount of surface (substrate) area and function not only as beds within which to grow the plants but also as a place where most of the bacteria in the system live that convert the ammonia. These bacteria, known as autotrophic bacteria, attach themselves to any surface they find. Their job is to convert the ammonia into nitrates. This is a two step process. First, one type of autotrophic bacteria converts the ammonia to nitrites by splitting the ammonia into nitrogen and hydrogen. The nitrogen (N) is then combined with oxygen (O2) found in the water in the form of dissolved oxygen and in this process forms nitrite (NO2). For the chemists reading this, it is NH3 or NH4 + O2 -> NO2 + H2. Both the nitrite and the hydrogen are released back into the water.

The nitrites (NO2) produced are also toxic to fish in relatively small quantities, just like the ammonia. So, the second bacteria comes into play to add some more oxygen to the nitrites converting them into nitrate (NO3). Note the spelling, nitrite (NO2), nitrate (NO3). Now, nitrates (NO3) are not very toxic to fish and generally, depending on the species of fish, they can tolerate 100 times more nitrates in the fish water than they can ammonia or nitrites. Remember, plants need and love (absorb) nitrates, so the nitrates won't stay or accumulate in the water to high levels unless there are fewer plants than needed to absorb (uptake) all the nitrates generated by the fish and bacteria processes in tandem.

This brings us to the solid fish waste. The good news is that nature provides. In this case nature provides us with another type of bacteria known as heterotrophic bacteria. Heterotrophic bacteria live in the water and attach themselves to any dead organic matter like uneaten fish food, dead plant roots or solid fish waste. Through a process called mineralization, the heterotrophic bacteria convert these leftovers into their component parts, which become nutrients for the plants. They also produce their own waste, which is ammonia; and it is converted by the autotrophic bacteria mentioned above into nitrates for the plants. In addition, heterotrophic bacteria help keep the water in the fish tank clean and clear. Heterotrophic bacteria also require and consume the dissolved oxygen in the water in order to live and do their work. So, heterotrophic bacteria take organic suspended solids in the water and convert them to dissolved solids that can be utilized by the plants.

It is important to note that the above processes each require and use dissolved oxygen found in the water (as do the fish and plants) and deplete it from the water as they go about their business. This dissolved oxygen must be replaced on a continuous basis or the process will not work properly. I will discuss the importance of ample dissolved oxygen in your system in a follow up post.

The plants, which are planted in the grow beds, receive the nutrient rich water containing all these wonderful ingredients including dissolved oxygen, uptake them along with some water and use them to grow. The remaining water now has reduced amounts of nutrients, and it is returned to the fish tank for use by the fish. So, the fish are fed, and their waste feeds the bacteria. The bacteria convert their food (fish waste) into bacteria waste that feeds the plants. The plants uptake the nutrient rich food provided by the bacteria. The water is cleaned in the process and returned to the fish. These symbiotic relationships are on-going as this is a recirculating aquaculture system that has both fish and plants as well as natures gift of beneficial bacteria working away, and it is known as Aquaponics.

Part Two will deal with System Design.

badflash
02-08-2011, 08:54 PM
Go with smaller to the point sound bites, we have a 10 second attention span.

Oliver
02-08-2011, 10:05 PM
badflash,

This is a non-ordinary format that has been set up to accommodate this tutorial. This particular post is perhaps the smallest in the series. This is a highly edited down version from the original text. I do not see any way to present it with less verbiage and still hold the intent, which is to provide newbies with enough information to build their own system.

I appreciate your input. I understand that you probably already know all of this and I can see how it would be a lot of unnecessary verbiage for you. But from a beginners point of view, which is the target audience, I needed to include enough detail so they can use it as their Aquaponics primer, which is why it is called "Aquaponics 101".

Oliver

badflash
02-09-2011, 04:20 PM
I'd recommend you send it to JCO to put up as an article off website as opposed to a regular post. I wasn't disparaging the content.

Oliver
02-09-2011, 04:42 PM
JCO set this area up for these posts.

Oliver

tem1160
02-09-2011, 07:18 PM
I kind of enjoyed the posts. when will you post the rest?

Oliver
02-09-2011, 07:49 PM
Thanks,

I will post Part Three on Thursday and maybe Part Four on Friday. The rest next week.

rfeiller
02-09-2011, 08:28 PM
i'm sure a lot of folks appreciate your info, i do.

rich

urbanfarmer
02-09-2011, 10:46 PM
Great content. I am bombarded with homework, but I hope to read over all of it by this weekend!

urbanfarmer
02-13-2011, 08:15 AM
Excellent overview. :D Also, I think a picture would be worth a thousand words here.

ak764
02-22-2011, 05:00 PM
Excellent info. I'm looking forward to learning a lot from this forum.

jackalope
02-24-2011, 11:43 PM
Oliver, thanks for posting this! I'm looking forward to reading more of your tuts!

oboeash
02-28-2011, 02:44 PM
Thank you for the information! I look forward to reading the next article as I'm begining to design and set-up my first aquaponics system.

JeffW
03-04-2011, 09:41 PM
u boys be nice now...or I will send my worm 101.....no serious interesting and dementia is always a problem for me so short or small I have to take notes either way :)

JCO
03-05-2011, 07:44 AM
JeffW, you write it, I'll print it and you know I will! :shock: :o :lol: :mrgreen:

builderguy1
04-08-2011, 01:07 AM
Thank you for putting this information out here. It has taken a lot of research just to find you. The information is in the process of helping me set up my first system. I havent found anyone near me who has tried.

urbanfarmer
05-01-2011, 11:50 AM
Thank you for putting this information out here. It has taken a lot of research just to find you. The information is in the process of helping me set up my first system. I havent found anyone near me who has tried.
Please put where you are from in your profile. I am sure there are people in your area!

gregw
05-09-2011, 07:54 AM
Hello, I'm new to your forum, thanks for these 101 articles. I have not read all of the posts yet so this might get answered later, but I'll ask while I'm thinking about it.
I'm interested in growing trout instead of Tipila, and I have unlimited well water at 57 degrees. Can I do a once through system instead of a recirculating system? This would give the trout the cool water they prefer.

rfeiller
05-09-2011, 08:56 AM
it is the nitrates that the plants want and the trout don't. trout are raised in close system quite frequently. to build up the nitrates to the levels necessary you would have to have a very slow dilution system. not open flow.

urbanfarmer
05-09-2011, 09:27 AM
it is the nitrates that the plants want and the trout don't. trout are raised in close system quite frequently. to build up the nitrates to the levels necessary you would have to have a very slow dilution system. not open flow.
Fish generally aren't bothered by nitrate levels. However, the ammonia and nitrite can kill the fish. These products convert to nitrate eventually, but until they do they are toxic to the fish at high concentrations.

rfeiller
05-09-2011, 09:39 AM
uf haven't found that to be true closed systems degrade the water quality and the condition of the fish. AP is a compromise, finding the point where both plants and animals can find a middle ground. the fish do not purify the water they remove only selected nutrients that they can utilize. trout do their best as do all aquatic animals in pristine water conditions, it's a sliding scale from there.
fish can exist in various levels of nitrate polution, but they are bothered by them as you would be if you lived in a sewer.

urbanfarmer
05-09-2011, 10:55 AM
uf haven't found that to be true closed systems degrade the water quality and the condition of the fish. AP is a compromise, finding the point where both plants and animals can find a middle ground. the fish do not purify the water they remove only selected nutrients that they can utilize. trout do their best as do all aquatic animals in pristine water conditions, it's a sliding scale from there.
fish can exist in various levels of nitrate polution, but they are bothered by them as you would be if you lived in a sewer.
Why must you do this to me... I'm not sure if you heard this from another aquaponics folklorist or if I am nipping potential aquaponics folklore in the KEISTER, but I will... here we go... :(

Fish adapted to live freshwater environments do not really pull minerals out of the water, but saltwater adapted fish do. Also, fish like trout live in both environments as part of their normal life cycle. This is the case in anadromous species or strains and the process is called smoltification. Please be more specific. However, I did not claim fish purify the water... I have no idea why you even mention such a silly thing.

Pristine water conditions sounds too subjective to be meaningful to anyone. Yes, fish grow best in water conditions that are best for fish. (see I can do it too). Anyway, what water conditions are "pristine" or best depends entirely on the context. Growing fish in green water with minimal pellet feed input can yield the SAME in fish growth and yield as growing them in RAS using 100% of feed input from pellets. In some situations, the green water application can work best while in others it doesn't. From a commercial standpoint cost and other business constraints come into play. Aquaponics is not like a t-shirt, there is no one-size-fits-all.

You are welcome to do whatever you want in your system, but please do no present your hunches as sound scientific fact especially to newbies who don't know any better. Nitrate toxicity in fish has been studied for over the last 30 years and the reproduction of experimental studies have repeatedly confirmed results. It is considered generally non-toxic. I can give you a list of studies a mile long dating back to the middle of the 19th century. Unless you are talking about fish in their larval stages, you are wrong in your implications regarding nitrate toxicity in trout or tilapia. Even in larval stages, the amount required to do damage to trout would be in the thousands of PPM if not HIGHER (it could also be lower, but unlikely). These numbers are just not found in aquaponics. I guess I could be wrong on that, but aquaponics more commonly has problems with very low concentrations of nitrate rather than high accumulations. Dr. Tyson's paper that I have referenced ample times even discusses this. I have observed it in my system, and I believe most others will say the same. Part of proper design of an aquaponic system is having an adequate ratio to remove ntirates. So, thinking nitrate will build up to dangerous levels is just plain SILLY. If you have this problem, you are doing it wrong rfeller.

If you wish to make claims regarding the nitrate toxicity in fish that contradicts modern science, at least state credible scientific references. If not peer reviewed research, at least research published in a credible scientific journal or commonly used introductory textbook for first year marine scientists and the like. Until then, can we please stick to the textbook facts about nitrate toxicity in fish? Thank you.

urbanfarmer
05-09-2011, 11:47 AM
Slight update on the Tilapia. I guess while in the eggs they could care less about the nitrate...

Because of their relatively impermeable chorion, the hatchability of tilapia eggs is largely unaffected by unionized ammonia (WOW! 101 PPM UNIONIZED) and nitrate.

REFERENCE
Rana, K.J., 1988. Reproductive biology and hatchery rearing oftilapia eggs and fry.

urbanfarmer
05-09-2011, 11:50 AM
Tilapia: biology, culture, and nutrition By Chhorn Lim, Carl D. Webster states that nitrate is not toxic to Tilapia whatsoever.

We should start a library on this dang forum to allow members to check out books. The following book would describe just about any issues regarding toxicity of fish: The toxicology of fishes By Richard Thomas Di Giulio, David E. Hinton

I already have a list of 6 books that are MANDATORY for my research and education on aquaponics, and these books cost $997 shipped total. Obviously, I am buying them 1 at a time, but it's still a lot for 1 student to pay for... my library card is maxed, any some of the newer or better books are unavailable to me.

keith_r
05-09-2011, 11:51 AM
i really don't understand this "folklore" thing you keep referencing...
re nitrate poisoning;
not folklore:
High nitrate levels create dangerous water conditions by oxidizing the iron atoms in hemoglobin, and by reducing oxygen supply to the blood stream and tissue. This condition is called Methemoglobinemia; closely related to the effects of DCS.

you may have some gardening cred's going on there.. but some of your fish info is.. well.. fishy

urbanfarmer
05-09-2011, 11:55 AM
High nitrate levels create dangerous water conditions by oxidizing the iron atoms in hemoglobin, and by reducing oxygen supply to the blood stream and tissue. This condition is called Methemoglobinemia; closely related to the effects of DCS.
Source? Reference? What is DCS?

Anyway, what's fishy is your reading skill, but you are talking about nitrite not nitrate. BIG OOPS! :lol: :lol: :lol: Brown blood disease, methaemoglobinemia, is caused by nitrite poisoning, sir.

NITRITE - HIGHLY TOXIC TO FISH
NITRATE - EXTREMELY LOW TOXICITY TO FISH, IN THE CASE OF TILAPIA NO KNOWN TOXICITY HAS EVER BEEN OBSERVERD TO MY KNOWLEDGE (which you are free to question)

I have for a long time thought that nitrate had some toxicity, but my knowledge was based mostly off forums and information given to me by hobbiest aquarium pet keeper types. They like to maintain the concept of nitrate toxicity in their folklore, which is probably unwittingly reinforced by pet store salespeople. I now seek my answers in scientific literature, which is far superior in both accuracy and consistency.

keith_r
05-09-2011, 12:15 PM
nitrAte can be toxic at high levels;
http://www.bio-elite.com/nitrogen_faq.htm
scroll down... have a peek.. open your mind

urbanfarmer
05-09-2011, 12:21 PM
nitrAte can be toxic at high levels;
http://www.bio-elite.com/nitrogen_faq.htm
scroll down... have a peek.. open your mind
You should take your own advice... the only scientific evidence I have read that has to do with ANY ill effects of high concentrations of nitrate (again outside the scope of what is found in aquaponics) has to do with reduced immune function.

If you look carefully, those symptoms are mostly related to secondary infections probably due to the onset of a reduced immune response. These problems have only been observed in very high stocking densities.

As most grade school students are taught, check your source.

A brief FAQ article with a doctors name slapped on it on a website SELLING products is not a good source. It's not even worth reading, and I would never read that kind of garbage unless someone has asked me to. A company with nothing more than a PO Box in South Africa is a terrible source for scientific information.

keith_r
05-09-2011, 12:22 PM
"NitrAte is relaatively non-toxic to tilapia;however, prolonged exposure to eleveated levels of nitrate may decrease the immune response and induce mortality (Plumb, 1997)

how's that for a reference...

urbanfarmer
05-09-2011, 12:24 PM
"NitrAte is relaatively non-toxic to tilapia;however, prolonged exposure to eleveated levels of nitrate may decrease the immune response and induce mortality (Plumb, 1997)

how's that for a reference...
It's excellent. Thank you. One thing to point out is it states "Nitrate is relatively non-toxic to tilapia"

I'm still not seeing a case for nitrate toxicity in tilapia, let alone any fish. Ironically, I stated this exact source above:


Tilapia: biology, culture, and nutrition By Chhorn Lim, Carl D. Webster
The above line of text is out of this book, I believe. Yes?

keith_r
05-09-2011, 12:27 PM
yes, at low levels it is non toxic, but at elevated levels and prolonged exposer.. there is plenty to show it will cause damage to fish... even tilapia, and that is something every budding ap enthusiast should know

first glance at data never reveals all details..

urbanfarmer
05-09-2011, 12:31 PM
Toxicity is toxicity and studies relating to concentrations tell us what the effects are at those concentrations. When it says it's not toxic, it means it's not toxic. What first glance at data are you talking about? Your source is not raw data, your source is interpreted from raw data; therefore, it is information. Information you should be disseminating not arguing against.

P.S. The 1 quotation from a scientific source you have referenced does not dispute anything I have said. In fact, it supports it. I implore you to PLEASE PLEASE search for more information if you recall that you saw something about nitrate toxicity in fish. If nothing more, it will help you learn.

P.P.S. I do get heated about these things when I am 99.999% confident about things. That doesn't mean I'm always right, but in this case I feel this is very remedial (like you said) except you have it wrong. If somehow the vast amount of scientific literature I have reviewed is all wrong, then by all means please make your case. I just don't see how a fact commonly accepted in the scientific community, which is not under debate or is controversial, is something you wish to argue against... anyway... let me know what you think bud...

keith_r
05-09-2011, 12:40 PM
so, i just want to get this straight.. you say nitrate is non-toxic to fish?

urbanfarmer
05-09-2011, 12:41 PM
so, i just want to get this straight.. you say nitrate is non-toxic to fish?
I have stated it is non-toxic to Tilapia and likely non-toxic or a very weak toxin to most freshwater fish species that are commonly farmed and cultured in RAS systems for food. Yes, in the context of what I have said in this thread.

keith_r
05-09-2011, 01:11 PM
ok then... here's a "real" study.. i'm not sure what is in your "folklore" category
http://www.atlantech.ca/public/articles ... uality.PDF (http://www.atlantech.ca/public/articles/Water%20Quality.PDF)

now.. levels must get staggeringly high to be toxic, and ras cultures have shown that tilapia will survive in 1000ppm, but bluegill will have trouble at 500ppm (i read the 500ppm part in an osu paper - ohio state univ... can't find it now.. ) the 1000ppm is something i heard from an aquaculturist so take it with a grain of salt..

keith_r
05-09-2011, 01:13 PM
the only other thing i really have to say on this is that if my nitrate readings were that high, i would think there was a problem with my system, being underfiltered, overstocked, overfed... all of which can cause a crash..

urbanfarmer
05-09-2011, 01:19 PM
I am reading, one sec please...

rfeiller
05-09-2011, 01:49 PM
Sorry if I did not intend to type fish, but plants remove nutrients what minerals are extracted by fish I am not certain to what degree. I am typing blindly on

my phone and didn't see the mistyped word. :oops:

urbanfarmer
05-09-2011, 01:55 PM
REVIEW OF: http://www.atlantech.ca/public/articles ... uality.PDF (http://www.atlantech.ca/public/articles/Water%20Quality.PDF)

Well, I call into question the quality of the research because as I read it certain things (based on my knowledge of water chemistry and fish biology) just screamed out at me. However, please note the researcher calls these same issues into question; therefore, I am not calling the quality of the researcher into question just the experiment itself. This happens A LOT in science. The experiment doesn't go the way you expected because, in the end, it is an experiment. Sometimes your control and changing of 1 variable ends up changing multiple variables. Sometimes you just make stupid mistakes and introduce error into your experiment (as is the case here). This can yield results that are not useful or not relevant to the original research question. I don't mean to painfully go over the fundamentals with you, but I have to preface my response with that...

A lot of the symptoms scream out to me nitrite poisoning, but in the discussion the researcher addresses this:

When nitrate levels were elevated due to addition of a nitrate salt or from nitrification, increased nitrite levels were observed. This increase in nitrite was most likely due to enhanced reduction of nitrate to nitrite caused by the elevated nitrate concentrations. (page 5)

In the end, I don't think toxicity was shown because the nitrate levels used did not kill the fish. The exception is the first experiment performed, but as the researcher stated it could have been caused by anything including ammonia or nitrite. If you notice when he examined a RAS with nitrate over 200 mg/L (ppm) the fish were not all dead and in fact in a commercial system. Clearly, something went wrong in his first experiment if there are commercial operations that don't have dead fish at these levels. To shed light on this I would like to explain there are bacteria that convert nitrate back to nitrite. In systems that have properly established cultures, the direction of this conversion is vastly in favor of nitrite to nitrate, but in his experiment it may not have been. This is further supported by his findings where the symptoms resemble nitrite poisoning. Coincidence or not, it should definitely raise some questions in your mind as it did for the researcher.


The changes observed in the nitrate treated fish most likely represent a pathological response as apposed to a generalized stress response. (page 6)
Again, the researcher has concluded that although nitrate MIGHT cause problems in RAS, it was not due to a nitrate toxicity. Instead, it was a secondary infection that did the fish in. As I stated earlier, I have seen scientific research discussing possible decline of immune system response in high concentrations of nitrate.


The water quality in this report was not mentioned, so it is not known if the nitrate concentrations were elevated. (page 6, end)
I was very disappointed when I read this. Maybe chloramine existed in the water and released large amounts of ammonia, chlorine, and nitrite into the water. Maybe the water contained other toxins that caused danger to the fish. I think you and I both know that pouring water out of your tap and then throwing some fish in is just a BAD idea. TSK TSK


Conclusion
The data presented here support the theory that prolonged exposure to elevated levels of nitrate may decrease the immune response, induce hematological and biochemical changes indicative of a pathologic response, and may increase mortality. If elevated nitrate levels are responsible for the pathologic changes seen in these fish, then management of recirculating systems must change to lower nitrate levels. The pathologic changes are sufficient to affect the normal physiology of the fish and will probably result in decreased growth and increased susceptibility to disease. These results however do not conclusively show that elevated nitrate levels are responsible for the pathology seen. Further studies demonstrating a dose response to nitrate levels should be conducted prior to making major management changes in a recirculating system.
Ultimately, I think this study is pretty bad. The experiment was poorly designed, and the researcher knows this as he describes all the flaws and leaves some out. Moreover, the researcher has no confidence in his findings nor can he make recommendations based on his findings. This is, in my opinion, not evidence to support nitrate toxicity in fish nor does it support the theory that nitrate causes a reduced immune response in fish (but perhaps does raise interest in the latter matter).

I think you will be hard pressed to find any evidence that supports nitrate toxicity in fish, which is why it is often presented as non-toxic in many textbooks. You have found one such textbook, and I am currently reading another titled "Aquaculture An Introductory Text (2nd edition)" and it was recently updated in 2009; so, I believe it to be up-to-date.

Please continue searching if you have the time and interest. I think you will find the process educational and enlightening. You will not regret it, and you will be better off for it. If you'd like, I can PM you a list of scholarly databases that are FREE to the public. I found they are about 10 years behind, probably why they are free, but that's not bad for us in aquaponics because we don't go into anything in depth and science has answered a lot of issues we face, at least to respect to aquaculture, hydroponics, and botany. I use other sources as well, but I have access to them as a student and it's not available to the general public, unfortunately.

rfeiller
05-09-2011, 01:57 PM
Sorry if I did not intend to type fish, but plants remove nutrients what minerals are extracted by fish I am not certain to what degree. I am typing blindly on my phone and didn't see the mistyped word. :oops: ididn't intend to do anything to you.
In my thread about nitrate levels I was hoping to see a pattern of this level of nitrates is best for this type of veggie/ plant and which works best with which type of fish. It's a given tilapia are best economically raised in the south or at least a state where they are legal. The rest of us will use other types of fish. This information works best to prevent newbies from failure.

urbanfarmer
05-09-2011, 01:59 PM
Sorry if I did not intend to type fish, but plants remove nutrients what minerals are extracted by fish I am not certain to what degree. I am typing blindly on

my phone and didn't see the mistyped word. :oops:
OH, that makes sense! I was like whoa that's a silly statement, he can't be serious! :lol:

I'm only half joking when I ask this, but did you mean to type nitrate or nitrite? That's what started this whole discussions, BY THE WAY.

Now I am wondering what you originally meant... what is the implication of "water purification" or lack thereof by plants. Before you answer, we are talking about plants AND bacteria helping clean the water for the fish, right? If so, what is the problem or shortcomings of this process that you might... be implying???

I think we need to start new threads on this. Maybe have someone move out discussion elsewhere like they did last time.

urbanfarmer
05-09-2011, 02:21 PM
The nitrites (NO2) produced are also toxic to fish in relatively small quantities, just like the ammonia. So, the second bacteria comes into play to add some more oxygen to the nitrites converting them into nitrate (NO3). Note the spelling, nitrite (NO2), nitrate (NO3). Now, nitrates (NO3) are not very toxic to fish and generally, depending on the species of fish, they can tolerate 100 times more nitrates in the fish water than they can ammonia or nitrites. Remember, plants need and love (absorb) nitrates, so the nitrates won't stay or accumulate in the water to high levels unless there are fewer plants than needed to absorb (uptake) all the nitrates generated by the fish and bacteria processes in tandem.
Oliver, there is no conclusive evidence that nitrate is toxic to fish whatsoever, and definitely not tilapia based on MY research.

Your numbers are out of context. A dangerous level of unionized ammonia at a pH of 5 versus pH of 8 translates to a difference in TAN (Total Ammoniacal Nitrogen) of a factor of 1,000. If you had an ammonia/ammonium total reading of 1,000 mg/L (ppm) at pH 5, it would be equal in TOXICITY to an ammonia/ammonium total reading of 1 mg/L (ppm) at pH 8, both at the same 80 degrees Fahrenheit for example. Does that seem strange? Well, it's true.

So, with that said, you can't just say fish can handle nitrate at 100x more quantity without being specific. A nitrate reading of 100,000 mg/L (ppm) is far different than 100 mg/L (ppm). But, more importantly nitrate is not toxic to fish or if it is, it has not been discovered and researched at any realistic concentration! :mrgreen:

rfeiller
05-09-2011, 02:45 PM
No it was nitrates not nitrites and to start this discussion was a good thing. With the commercial breeding of fish you have several objectives, three of which are growth rate, health of the animal and size it attains. In comparrisons that i did myself using hundreds of fish the results were always the same slowed growth rate, more prone to breaking down, and stunted growth. Always in proportion to level of nitrates.

urbanfarmer
05-09-2011, 03:56 PM
No it was nitrates not nitrites and to start this discussion was a good thing. With the commercial breeding of fish you have several objectives, three of which are growth rate, health of the animal and size it attains. In comparrisons that i did myself using hundreds of fish the results were always the same slowed growth rate, more prone to breaking down, and stunted growth. Always in proportion to level of nitrates.
Disease, genetics, temperature, feed, light, tank mates, starting size, and SO MANY OTHER FACTORS could play a role. Without a well designed experiment to study the variables in question any evidence observed is little more than anecdotal, unfortunately.

Hundreds if not thousands have come before you, in a scientific manner, and they have attempted to prove the claims you just made/implied. They have all failed. I don't think what you observed had a correlation with nitrates and there was definitely no causality involved. I suggest to you other factors were at play that either were not accounted for and/or could not be perceived.

cedarswamp
05-09-2011, 04:58 PM
No it was nitrates not nitrites and to start this discussion was a good thing. With the commercial breeding of fish you have several objectives, three of which are growth rate, health of the animal and size it attains. In comparrisons that i did myself using hundreds of fish the results were always the same slowed growth rate, more prone to breaking down, and stunted growth. Always in proportion to level of nitrates.
Disease, genetics, temperature, feed, light, tank mates, starting size, and SO MANY OTHER FACTORS could play a role. Without a well designed experiment to study the variables in question any evidence observed is little more than anecdotal, unfortunately.

Hundreds if not thousands have come before you, in a scientific manner, and they have attempted to prove the claims you just made/implied. They have all failed. I don't think what you observed had a correlation with nitrates and there was definitely no causality involved. I suggest to you other factors were at play that either were not accounted for and/or could not be perceived.

First I have to agree with rfeiller, as I've observed the same. Can I prove it scientifically? No but I've observed in my own tanks that fish are healthier in general when water is changed often enough to keep nitrates below 40 ppm. Isn't the object to mimic a natural ecosystem as closly as possible? Elevated levels of nitrates in nature reak all kinds of havoc on the ecosystem, so why wouldn't we strive to keep them lower in our systems?


Alright just for you some actual science. :D
http://ehp.niehs.nih.gov/realfiles/members/2005/8056/8056.html

rfeiller
05-09-2011, 05:22 PM
If I am not disputing what you have read you doing exactly what a researcher does. All I do is relate my experiences. Take it with a grain of salt, but if you follow my information pertaining to fish you will be ahead. How's that for arrogance!! :D

If I were doing a study on possible toxic substances I would use the more sensitive animals to toxins for quantitative & qualitative studies.

urbanfarmer
05-09-2011, 05:32 PM
If I am not disputing what you have read you doing exactly what a researcher does. All I do is relate my experiences. Take it with a grain of salt, but if you follow my information pertaining to fish you will be ahead. How's that for arrogance!! :D

If I were doing a study on possible toxic substances I would use the more sensitive animals to toxins for quantitative & qualitative studies.
Well, all I have to say is I hope you're not CHARGING anyone for that information! :lol:

Sure, you can use different creatures, but what if I want my research to be relevant to something very specific. For instance, what if it's costly to remove nitrates from the system given government restrictions and actually material/labor costs? What if the reduction in growth rate is too small to justify the added cost to remove the nitrates or maybe increasing/decreasing the frequency of nitrate removal? Often times, scientific research is employed in commercial situations to enhance profitability or prevent damage to the environment or people. There are no hard fast rules on how to do it except of course following the scientific method, and even that isn't ironclad.

rfeiller
05-09-2011, 06:31 PM
Hell no, didn't cost you a cent; cost me thousands!

You've just brought up some interesting issues. :)

keith_r
05-10-2011, 06:30 AM
it's like arguing with a republican!

if my system nitrAtes get high, i'm going to try to identify the problem.. if they were up over 400 i'd be doing partial water changes and adding more plants..

i've been trying to say that you'll find contradictory documentation and studies on just about any subject, but actual experience and observation by these "folklorists" you keep bringing up is where much knowledge started

rfeiller
05-10-2011, 07:43 AM
As I said UF is doing what a researcher does and he does it well.
I rely on my histories successes and failures to guide me and I share those. I'm sure there are those that totally disagree with me. I look to see the fruits of their endeavors and judge them by that.
As a marine Bio major ( didn't t finish,) you wouldn't believe the crap science had to offer and so much of hard science has been modified or rejected altogether. Do I ignore science of courses not, but I don't blindly accept it either.

keith_r
05-10-2011, 08:56 AM
As I said UF is doing what a researcher does and he does it well.
I rely on my histories successes and failures to guide me and I share those. I'm sure there are those that totally disagree with me. I look to see the fruits of their endeavors and judge them by that.
As a marine Bio major ( didn't t finish,) you wouldn't believe the crap science had to offer and so much of hard science has been modified or rejected altogether. Do I ignore science of courses not, but I don't blindly accept it either.

and that's been my point.. the "science" of ap is just too new.. experience and results are leading the way... science tries to prove or disprove those results

grimsteph
05-10-2011, 09:03 PM
I have to disagree with Urbanfarmer on the subject of nitrates. There have been numerous studies on nitrate levels and how they impact fish. I actually remembered this from my biology classes as an undergrad, but I did a quick google search and came up with the following from several studies:

- Elevated nitrates above 100 ppm appear to substantially reduce antibody response in fish.
- Elevated nitrates above 200 ppm appear to cause damage to internal organs and particularly kidneys.
- Elevated nitrates above 100 ppm appear to negatively impact growth rate.
- Elevated nitrates at 200 ppm for 7 weeks tends to be fatal to fish.
- Elevated nitrates (no ppm given) tend to hamper oxygen absorption in fish.

urbanfarmer
05-10-2011, 09:32 PM
I have to disagree with Urbanfarmer on the subject of nitrates. There have been numerous studies on nitrate levels and how they impact fish. I actually remembered this from my biology classes as an undergrad, but I did a quick google search and came up with the following from several studies:

- Elevated nitrates above 100 ppm appear to substantially reduce antibody response in fish.
- Elevated nitrates above 200 ppm appear to cause damage to internal organs and particularly kidneys.
- Elevated nitrates above 100 ppm appear to negatively impact growth rate.
- Elevated nitrates at 200 ppm for 7 weeks or more tends to be fatal to fish.
- Elevated nitrates (no ppm given) tend to hamper oxygen absorption in fish.

I am pursuing a Masters of Science in Environmental Science, with a major in Soil and Water, and 2 minors, Aquaculture, and Botany. I have not yet reached curriculum discussing water chemistry as it applies to fish nor fish biology (a course I am very much looking forward to). Yes, my very own custom tailored Aquaponics degree. :ugeek: :ugeek: :ugeek:

With that said, understand I have been left to my own devices until the time comes that I have the above stated education in a state-of-the-art manner. Now, please state any specific research or references otherwise so we can all act as peers reviewing said literature. From the posts in this thread I just reviewed research discussing 200 ppm nitrate on fish. So, please explain... If it is scientific fact that more than 7 weeks at 200 ppm nitrate levels is fatal to all fish in all stages in their life cycle, then how does one researcher state that he observed and studied fish in a commercial operation that consistently had over 200 ppm of nitrate? You would imagine this guy would be out of business with all the fish he has left?

I have yet to see evidence to conclude nitrate is toxic to fish, especially as it applies to Aquaponics.

I don't think it's safe to assume 200 ppm nitrate is toxic or even fatal to fish in any adult stage of their life cycle and sensitivity to nitrate is variably dependent on species and strain for pre-adult stages in their life cycle. FOR EXAMPLE, TILAPIA ARE SUPER FISH.

Anywhooooo, I wanted to thank you from the bottom of my heart for joining the discussion. I think we need more people interested in all our lively debates. With more of us searching out information and presenting it in a forum manner for discussion, I think we can all advance our learning faster and deeper than without each other.

P.S. Was your undergrad in biology or the like? Just curious how much I need to pick your brain. :mrgreen:

urbanfarmer
05-14-2011, 07:46 AM
If I were doing a study on possible toxic substances I would use the more sensitive animals to toxins for quantitative & qualitative studies.

Detection of Mercury in Aquatic Environments Using EPRE Reporter Zebrafish (http://www.springerlink.com/content/w043037p48325184/)

Abstract
It has been proposed that transgenic zebrafish could be designed to detect low levels of chemical contaminants that cause oxidative stress in aquatic environments, such as heavy metals or pesticides. In this paper, we describe such a transgenic zebrafish that produces a luciferase–green fluorescent protein (LUC–GFP) fusion protein under conditions of oxidative stress. The reporter gene expression is under the regulation of the electrophile responsive element (EPRE), which activates gene expression in response to oxidative stressors. The GFP component of this fusion protein allows us to visually detect reporter gene activity in live animals to determine if activity is localized to a particular tissue. The luciferase component is capable of returning a quantitative assessment of reporter gene activity that allows us to determine if reporter gene activity is directly correlated to the concentration of the chemical inducer. We have tested this reporter construct in both transient and stable transgenic fish after exposure to a range of HgCl2 concentrations. GFP expression from the EPRE–LUC–GFP construct was inducible in transient assays but was below the limit of detection in stable lines. In contrast, we observed inducible luciferase activity in both transient assays and stable lines treated with HgCl2. We conclude that the EPRE is capable of driving reporter gene expression in a whole animal assay under conditions of oxidative stress. Furthermore, expression was induced at HgCl2 concentrations that do not result in obvious morphological defects, making this approach useful for the detection of low levels of oxidative contaminants in aquatic environments.

chesapeakebaybe
07-14-2011, 07:49 AM
Oliver, I can't thank you enough for taking the time to make these posts (and thanks to JCO for setting up this section of the forum). As a newbie, this information is pure gold!

I'm done reading the first article, and am now onto the rest of this fabulous series.
:-)