Aquaponics 101-Part One: The Process

[rfeiller]

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]

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]

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]

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]

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]

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! 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]

nitrAte can be toxic at high levels;
http://www.bio-elite.com/nitrogen_faq.htm
scroll down... have a peek.. open your mind

[urbanfarmer]

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]

"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]

"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?