Saltwater aquaponics?

[grantmcd]

Hi all,
I was wondering what the possibility would be of running a salt water system? So I want to raise salt water fish like sole or cob and I want to know if it is possible and what plants should I use to filter the system?

Any help would be appreciated.

[jackalope]

I've heard of that, and I think there are a few veggie plants that will tolerate the salt water .... I'd Google, Ixquick, or check You Tube to see if I could find any takers ;)

[badflash]

No too many crops that will be worth growing in salt water. There are some chinese plants, but not many. I also have not heard of anyone trying those fish in aquaponics.

[urbanfarmer]

Well, as far as the fish, you could use Tilapia! :D

http://dx.doi.org/10.1016/0044-8486(92)90253-H

Seaweed is an expensive item, but typically needs to be dried and packaged before it is sold, which may be costly. This would be better marketed toward ethnic communities.

[dufflight]

Few people have talked about it. Think growing seaweed for the regular garden or AP system and take out the solids. If the solids were watered down to dilute the salt if would make a good fert for the dirt garden.

[rfeiller]

twenty-five years ago there was a saltwater set-up in the carribean where seaweed and conchs were grown for commercial purposes. it was at that time quite successful.

as far as tilapia in saltwater, if in hawaii you can find them in tidepools of brackish water. there is a lot more money in abalone, conchs, etc. then in tilapia. seaweed brings in a lot more then lettuce.

[urbanfarmer]

Few people have talked about it. Think growing seaweed for the regular garden or AP system and take out the solids. If the solids were watered down to dilute the salt if would make a good fert for the dirt garden.ld
The salts would eventually build up to toxic levels and kill off your plants. The salt content would be so high the plants would not even be able to take in water! Remember, seawater is 3.5% salt. If you drink a lot of it you die. For instance, if you drank 6.9 Liters of seawater or your salty aquaponic water, you would end up dead.

http://wiki.answers.com/Q/How_much_salt_will_kill_a_person (it says 40 teaspoons, I did the conversion for dramatic effect) :ugeek:


Interesting fact: Salt kills weeds, and everything else in the area. In fact, the ancient Romans routinely salted the lands of their conquered enemies. Specifically, they so heavily salted the ground around Carthage that the area is still desert.http://wiki.answers.com/Q/How_much_salt_do_you_add_to_water_to_kill_weeds

Suffice it to say, you don't want to do that. IF you still had your heart set on using the waste product on your garden, you could distill your aquaponic water, which would leave behind the solids (salt and some of the micro-nutrients), and give you some of the other nutrients assuming they didn't volatilize into the atmosphere! :-)

Why do you want to do saltwater aquaponics, anyway?

[rfeiller]

hydroponics is not a closed system, so why is aquaponics? i understand there needs to be a certain level of nutrients in the water to feed the plants, but no matter what, unwanted levels always build up and need to be diluted.

[urbanfarmer]

Ah, it seems my question has uncovered a false assumption you have made by comparison of a similar method of growing.

In hydroponics, you have to change the water because of several reasons, but 1 being coincidentally the same as what I listed above earlier. The SALTS build up that make up the INORGANIC nutrient solution filled with dissolved solids you use to feed the plants. As these salts reach fatal levels, the plants are unable to take up water or nutrients and DIE. So, the only solution is to change the water.

In aquaponics, the nutrients are mainly derived from the processed waste of the fish by microorganisms. The nutrients, although water soluble, are not SALTS, but rather ions that get eaten up by the plants. When nutrients are provided in an ORGANIC form they are readily broken down in organic systems and therefore do not cause fatal buildups if balanced. It's all more complicated than this, but remember, it's a miniature ecosystem you are building! The cycle is self-contained; therefore, you do not have to waste water like that (and in fact is one of the main reasons behind why aquaponics was researched at the University of The Virgin Islands and why it has been so successful in Australia).

With that said, you should watch your levels. If your levels are out of whack such as nitrate, you will want to change out some water. This water can be used to fertilize soil plants or in pure hydroponic systems where relatively high levels of nitrate for fish are inconsequential to the plants. My first aquaponic setup was a 10 gallon tank. I must have spiked the nitrate up to 800ppm at one point. I lost 1 fish of 35; afterward, I used most of the water in a hydroponic DWC bubbler system. The plants did great, and the remaining fish thanked me for it! LOL

[badflash]

You always need to watch your system and compensate. Systems are never perfectly balanced, but the need to do water changes are dramatically reduced in aquaponics. Normally the levels get too low for the plants, not too high for the fish.

[urbanfarmer]

I have done some more research as far as the plants go. There are a lot of ornamental saltwater aquarium plants you can grow that sell for quite a bit retail. I have seen some SMALL plants selling for $15 online. Also, they don't even require a medium or a raft, you can just place them IN the water! You have inspired me to build a small saltwater aquaponic setup in the next few months to try it out. :D

[dufflight]

Just a note on sea salt. Because it contains a lot of trace not found in soil due to leeching over the years it is added to AP, hydro and soil gardens. Even after a tsunami that floods crops lands they have found that the plants grow a lot better now. Different salts can cause problems for your plants. I put 160kgs of sea salt into my AP system and the plants have used a lot of this and it probably needs another 100kgs.

[urbanfarmer]

Just a note on sea salt. Because it contains a lot of trace not found in soil due to leeching over the years it is added to AP, hydro and soil gardens. Even after a tsunami that floods crops lands they have found that the plants grow a lot better now. Different salts can cause problems for your plants. I put 160kgs of sea salt into my AP system and the plants have used a lot of this and it probably needs another 100kgs.
Well, as you know in aquaponic systems we have trouble getting our Potassium. Interestingly enough:


Potassium deficiency can be greatly alleviated in the presence of sodium but the resulting sodium-rich plants are much more succulent than a high potassium plant. In some plants over 90% of the required potassium can be replaced with sodium without any reduction in growth. http://4e.plantphys.net/article.php?ch=t&id=289

And, since the plants take up Chloride, you are basically letting the plants eat up your sea salt (NaCl). Neat, huh? :ugeek:

[dufflight]

And remember the fish like the salt too. :mrgreen:

[gosmith]

Personally, I think this is a great idea and would love to see some experimentation being done. Why should you have to live by an ocean to enjoy fresh local seafood? Flood and drain grow beds could be easily adapted with sloped gravel beds to become rocky intertidal zones to grow various shellfish and other filter-feeders, as well as to provide habitat for marine worms, ghost shrimp, and other fauna that could be fed to salt-water fish living in the tanks.

Benthic algae (bottom anchored seaweeds) grow at incredible rates when nutrients and temperatures are right and can go directly into dirt gardens as fertilizer, but can also serve as a food source for various crustaceans and fish. There are also many varieties around the world that are eaten by people, so don't think you can't grow edible plants in a salt-water system. Nori is probably the most commonly known in the west, since the roasted sheets are used to wrap sushi. It's also good in soups and salads. High in calcium, iron, phosphorous, potassium, and lots of vitamins. Dulse (Palmaria) is harvested in Europe, especially Ireland and Scandinavia, and used in soups, salads, and stir-fry. Kombu supposedly tastes like bacon when it is roasted, although I've never tried it. There's a ton of others. Some of this stuff sells for $20 or more per dried ounce. Google "edible seaweed" for info and recipes.

Dissolved nutrients can also be taken up directly by phytoplankton to become the basis of a food chain to feed various zooplankton, including shellfish and crustacean larvae spawned in the growbeds, which in turn feed the fish species you want to raise.

I do think it might take some tinkering to find all the right species to pull this off while creating a balanced system, but that is where the fun is. My guess would be that larger would be better.

Gary

[korosho]

We've got a small aquaponics setup here at home, but a little fish tank and some sprouts.
I really like the idea that the concept puts forth. I've put some time into different ideas and concepts, so it's neat to see people coming up with saltwater too.

I live near an ocean, with not a lot of good growing soil around. to be able to convert tidal pools, areas with less momentum than full ocean, but as a salt water plant hosting water source.

I see posts by people who suggest growing seaweed, and salt resistant plants, which all makes sense, but shouldn't there be an easy solution?

Can we not filter out the salt, ionically bond it to metal before it is passed to the plants?

My idea spreads from covering small ocean inlets with growing medium and catwalks. Same with small ponds and lakes, why not use ~1/3 of their surface area as a growing surface?

[JCO]

korosho, please go to your profile section and put in the city, state/country where you live. There might be members close to you. :mrgreen:

[urbanfarmer]

I forgot to mention that if the plants uptake the Na+ ion from the water, the Cl- ions will typically find each other and off gas assuming there is more uptake of Na+ ion than Cl- otherwise if the plant grabs Cl- first it will leave the Na+ in the water. Since there would be more Na+ in the water the Cl- would not gas off as it would be playing around with the Na+ and staying very soluble.

[korosho]

I forgot to mention that if the plants uptake the Na+ ion from the water, the Cl- ions will typically find each other and off gas assuming there is more uptake of Na+ ion than Cl- otherwise if the plant grabs Cl- first it will leave the Na+ in the water. Since there would be more Na+ in the water the Cl- would not gas off as it would be playing around with the Na+ and staying very soluble.


I like it!

the introduction of seawater to plants shouldn't be so bad given the right circumstances, some companion plants that deal well with Cl gas wouldn't be a bad idea.

My idea seemed to be under the scene of a aquaponic style growing system immersed in tide pools, with controlled growing beds that can allow each bed to be electrolyzed, allowing the plants to access the pure water without necessarily needing to deal with the salinisation at all.

imagine growing plants in essentially very weak salt water batteries..

[badflash]

Just make sure your plants are salt tolerant. Many are not. Jackalope wiped out his system once treating sick fish with salt.

[jcx]

Sole (Brachirus Salinarum) can tolerate brackish water so you could run a pretty low salt level. I found it listed as a native AUS fresh water fish also. Maybe be able to acclimate them to fresh water.

[mespe]

For instance, if you drank 6.9 Liters of seawater or your salty aquaponic water, you would end up dead.


ummm, if you drank 6.9 liters of freashwater, you'd be dead too!

[jcx]

Youtube Mantis shrimp. It's the most powerful animal in the word by size. If you do salt water you should get one, they are awesome.

[urbanfarmer]

For instance, if you drank 6.9 Liters of seawater or your salty aquaponic water, you would end up dead.


ummm, if you drank 6.9 liters of freashwater, you'd be dead too!
Was that a really bad joke? I drink more than that in a day if I'm working out.

[cenapatuct]

Guys,I was wondering: What if you replace the plants in the saltwater AP system with oysters or clams,for example? Do you think they can filter the water better than plants and feed(thus grow) using the dissolved nutrients in it? And if so,would you even need to remove the solids and run the water through a bio-filter before you flood the DWC tanks ( in this case used as improvised tide pools)?

[urbanfarmer]

Can you be more specific? Do you mean the oysters / clams would remove the nitrogenous compounds?

[cenapatuct]

I don't know,that's what I'm asking too!
Seaweed is a very niche market product,but growing shelfish,on the other hand,can be quite profitable(not to mention ocean fish in the fish department :mrgreen: ). I know some of the guys out there use freshwater clams in their DWC systems for additional filtration and it works pretty good. Of course those systems are mainly about plants,but could it work the other way around-could plants be used as an addition in a predominantly shellfish system for succesfully filtering the fish waste?

[urbanfarmer]

I did a quick search, and it looks like they are filter feeders meaning they will eat plankton out of the water. It mentioned oysters were such good filter feeders they improve water quality and were used to remove pollutants. Exactly what does it do? No idea. I guess you would basically have a green water situation with the oysters/clams in there. More of a pond than an aquaponic system, but it could work.

[Daniel]

That's a great question and one that could use a lot of research since there are a lot of saltwater fish that will not live in fresh water but would be great to raise. Cobia would be my choice. What research I have seen has focused on plants that thrive on ammonia rather than converting it to nitrates. One such plant is ulva, or sea lettuce. This does not have to be dried and is useful in a variety of ways including salads, soups, and even in ice cream. No, I don't think it is ulva flavored ice cream. It seems to be a thickening agent. Further research could be done in experimenting with gradually increasing the saltwater tolerance level of fresh water vegetables. Research has already been done in lowering the salenity level for some species of saltwater fish successfully. So a happy medium might be realized with some fish and some more common food plants. The other comment previously made about dried seaweed is certainly true. Here's a link to the use of seaweed in saltwater aquaponics. http://www.aquaponicsjournal.com/docs/a ... inator.pdf (http://www.aquaponicsjournal.com/docs/articles/Seaweed-is-Common-Denominator.pdf)

[robertcoogan]

urbanfarmer is right. His post [Posted: Sun Oct 10, 2010 10:10 pm] mentions that some aquarium plants can sell for quite a bit. I was watching a reality TV show one night and one fist-sized lump of coral was elling for almost fifteen thousand dollars. No joke! A lot of dough, but it might be a slow growing process. I posted this to another forum on the subject:

I found this link which says that corals like a high ph:

http://www.coralscience.org/main/articl ... reefs-grow (http://www.coralscience.org/main/articles/biochemistry-2/how-reefs-grow)

This paper says that too high a ph could inhibit the rate of photosynthesis in seaweed, due to the high ph causing lower CO? levels:

http://www.nrel.gov/docs/legosti/old/1820.pdf

I want to try this as well. It looks really interesting, and if one could successfully raise coral, you could make some really good money. Some people will pay top dollar for prize corals for a decorative fish tank.

So in freshwater aquaponics, algae and a high ph is your enemy. But in saltwater, it is your friend!

I hope this helps -

UPDATE: I found this BBC story on a saltwater fish farm in the Sahara, pretty interesting:

http://www.bbc.co.uk/news/world-middle-east-19942183

[dead_sled]

Here is a link showing some of the salt water aquarium plants:
http://www.aquacon.com/vip.html
There are some pretty sweet plants in there. 8-)
Maybe these can be grown is a S-AP configuration.

[Moondancer]

http://www.pfaf.org/user/plantsearch.aspx has an option to search for plants that tolerate salt spray. These are probably either coastal terrestrial plants or brackish swamp/marsh ones rather than actual marine dwelling plants.

I think I might experiment in a few years with a brackish setup. Learn how to save seed and slowly increase the concentration from brackish to saline. Saving the best seeds after each increase should eventually lead to marine growing cultivars. Not crazy about fish but LOVE shellfish!

[Personoponics]

I think it would be very interesting to have an integrated aquaponic system. Maybe it should be called mariponics, since it is more interested in marine plants and seafood than aquatic fish and terrestrial plants.

I think it would be cool to have, say, a tank of salt-water fish, such as tilapia, or dare I say, salmon, if the operation was big enough, and have that waste flow to shellfish and invertebrates like crayfish, crabs, seacucumbers, abalones, and clams and such. That way, the solids are eaten up by those animals before going to the nitrogenous breaking bacteria and then salt-tolerating plants, seaweed, or marine algae. Kelp could be grown hydroponically, right? Maybe have kelp starters and put those on little anchors or upside down floaters in a tank of salt water. The kelp and smaller seafood could maybe even be used for feeding the larger fish! :D

I also like Moondancer's idea of breeding salt-tolerating strains of terrestrial plants. Maybe over several generations, the plants would be better suited for salt. Imagine, watermelon already salted before you cut it!