Aquaponic Gardening

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I just tested my "Total Iron" in my system and it shows zero (0) ppm.

Has anyone tried putting a small iron pipe or pipe caps in 3-4 media beds?I have about 30% of my expected grow beds working.

This may leech iron into the system.

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Hello Dan,

They do not provide any measurable iron. You really need to add a very small amount of chelated iron when you see the need (your plants will tell you). In the meanwhile, in a new system, you can always add a little Maxicorp with Iron. This should help.

God bless

it is hard to say if placing iron into a system will provide plant usable iron or not, and even if it does, it would take a long time to do it.  You also need to make sure that it is pure iron without any other metals that would be bad for the fish (like the zinc in the galvanized coating on lots of iron pipe.)

I would use the chelated iron.  But how did you test the total iron?  Is the test accurate enough to really measure the amount needed?  Are you plants showing signs of iron deficiency?  What is your pH? 

I think people on the forum should take an introduction to chemistry course: FeO or Fe2O3 (pretend the numbers are sub-scripts) or rust as it's commonly called would be the product of this reaction--and it is not available for the plants root system. In other words, putting iron in a aquaponic system can only kill your fish (if it does anything at all). Chelated iron is soluble, I think, becuase it will become a Fe (iron) ion, and thus is able to be absorbed by the plant-root.

I was thinking the same thing. I was going to put some metal pipes in that i could flow water through or bypass when the iron levels go up. But im not sure if it would work or not, so i will be watching this post to see what everyone says about it. I would rather not have to add iron or any other chemicals to the system if there is a way to avoid it.

Plants can really only uptake iron in it's ferrous form (Fe2+) the only iron you could hope to get out of a metal pipe in relatively oxygenated water would be ferric iron (Fe3+) which will do nothing for your plants AT ALL, and certainly has the potential, under the right conditions to do some harm to your fish. (Mostly accumulate on their gills and cause problems and/or death). 

Iron chemistry is rather complex (no pun intended) as it will form complexes with just about anything it comes into contact with...So lots and lots of variables...but even if this were not the case, you still could not really get any plant usable ferrous iron from a pipe in aerobic conditions.

You would need an anoxic environment, a bit of time, and certain falcutative anaerobic bacteria not commonly found in your typical AP system (I'm simplifying, as they may be present in the sandy anoxic sediments at the bottom of your grow bed). But say you did convert the Fe3+ to Fe2+ anaerobically...Then you would need lots of humic acid or tannins to complex with the ferrous (usable) iron and a nice low pH to bind it, since as soon as it hits oxygen rich water it wants to (and does), turn back into ferric (unusable) iron. pH, temps, and organic acids slow this process down a bit...but without proper conditions your Fe2+ will turn back into Fe3+ in a matter of seconds...but such is the Iron Cycle... 

Now, that all being said...there are potential ways to get usable iron from rust, in an AP system, but it's no picnic. It may involve building and adding on some Ruth Goldbergh type contraptions and lots can go wrogn if you don't have a good handle on the chemistry going on in your AP system (not just the nitrogen cycle either, I'm talking some pretty niche stuff) and know why you are doing what you are doing the way you are doing it. I highly doubt that most folks would want to even go there...

At any rate sticking some iron pipes in your system wont cut it. (And yes I said wrogn on purpose:)

JUst get the chelated form of iron and it works great.  I add it when my leaves come out yellow.  I think many others do also

The plants are just starting to show signs of yellowing.

I have a test kit for total iron and my PH is about 7.5 ppm.

There is a hydroponic shop in Gainesville (very expensive). I will shop by and see if they have chelated iron.

Thanks for the comments.

Dan, if you can...get any product that is not the EDTA chelate (this was one of the first iron chelating agents, but has 'recently' been proven to be a little toxic to plants...but folks still have warehouses full of the stuff and still sell it sometimes).

Any of the other chelating agents would be a bit better, like...EDDHA or HEDTA or even DTPA. (Though the first two would be best...DTPA is suspected to be toxic to plants, but this has not been proven yet). Any self respecting (and expensive) hydroponics store operator will/should know this though, and will hopefully do you right...

If the yellowing gets real bad by the time you get your iron chelate, you can foliar feed it on the leaves as well as add it to the system water (2-3ppm would do). The plants seem to react faster to the iron when foliar fed as opposed to when it's added to the nutrient reservoir (or in this case AP system) water. Mine do anyways.

WOW after reading all these post, I feel like i just took a chemistry class. I thought the beauty of AP was the simplicity. This is going to take some education, or i could save myself $30,000 and just ask questions on here, so i dont get it (wrogn). Thanks Guys Now i wont put a metal pipe in my line.

The complexity of the simplicity makes all life--and all of the wonders that spring from it--beautiful. Sorry, just watched two episodes of Carl Sagan's Cosmos.

Gilliam said:

 ...I thought the beauty of AP was the simplicity...

Well said Eric, I'm still in the design/build stage. I have 3 out of 6 IBC's level and i am starting to plumb them up. I'm trying to work it all out, so i can easily go from summer to winter. In the spring, summer, and fall, I want to run with a flood and drain grow bed and a raft bed as well. In the winter when it is -30 deg. I want to rotate my effluent pipes back into the barn and run only 1 or 2 totes with a minimum # of fish and no plants, so i don't have to heat alot of water.

So simplicity for me was out the window before i ever got started, But when my system is up and running it will be beautiful.

Tony another good winter strategy to add to that, is to switch to constant flood in the winter. Since the hydtroton or gravel will act like a cold sink (heat sink in reverse) for your system water that (your spending good money to heat) in a flood and drain scenario.


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