Backyard Aquaponics
A place to discuss aquaponics

Not sure if this is the right place to post this so if its in the wrong section I apologise in advance.

I was visiting a friends hydroponics farm yesterday and as I was being shown around he started talking about how he's having trouble with trace element toxicity in his system atm. Breaking it down he was basically saying that the crops that he grows through winter have a reduced ability to take up manganese so to avoid this situation he increases the managanese concentration in his nutrient mix and now, because it's starting to warm up, he has to drop it again because the plants (lettuce) were starting to show signs of managnese toxicity because their ability to take up the nutrient was increasing as the weather warmed up.

It all seemed like a lot of trouble and I started thinking I had never heard of any comments regarding trace elements or trace element deficiencies in aquaponics. So I was wondering if anyone knows of anything that may have been done to study this in aquaponics systems that I could have a read of? I've done a search on it in Google and come up with a lot of people saying things like nitrates and nitrogenous products are no problem but trace elements may be a problem, and one source that says they add seaweed extract or chelated iron (that was in Joel's Gardening Aust. article).

TIA

Simon

its hard to test for most trace or micro elements.

i haven’t came across of any studies of it either...

its seems like to be not a big problem in most systems.

i am sure that some micro elements come from the tap water. i am sure one that are in-mobile in soil wont be found in the tap water. and from what i recall that manganese is a in-mobile micro element.

currect me if i am wrong

-df

Two main elements have been found missing in AP (not in the fish food pellets)

Iron - this has been overcome by using regular doses of chelated iron (one or two spoonfuls a month)
Potassium - several sources for this, but I just buy some cheap overripe ones from the market and bury them in the GBs, one/GB each month with the skins removed

I also use an organic mineral supplement (MinPlus) - spoonful/GB/month...seems to work for me

There are other additives that are used - Seasol, seaweed extracts etc...others may wish to put forward how they apply them

also at home depot or stores like that have tabs for ponds to add nutrients for pond plants. i looked at one, flourish i think it was called, it had quite allot of macro and micro nutrients.

-df

ps sorry about all those repeats

I'm a seasol man myself, about a gloop every 2 months in winter and a little more often in summer. Not very scientific, but it seems to work.

+1

Hey OzV, chelated iron, seasol and bananas are about it really.
If u use scoria as ur grow media, I am sure minerals are leached into the water for the plants, and fish too i spose, but I can't quantify it. Just makes sense that it would be the case.
My whole problem with hydro is dicking around with chemical nutrient additives. I don't care what the hydro ppl say, it aint natural and as per ur friends situation, ur always trying to doctor the mix and second guess mother nature.
My mum spent a lot of time at Coles Bay over there, nice part of the world.

I remeber a talk which mentioned that many trace elements and such were locked up in coral... So I have coral in areas where there is a lot of water movement in the hopes that as they SLOWLY dissolve they will also release these into my system... no bad news as of yet...

+1 for a gloop of seasol

if your using gravel you'll find a lot of them are probably in the dust it comes with.
i'd be interested in seeing say, a 3 year old NFT setup vs a gravel.

+1 for not washing dirty gravel

@ ell

There are probably more problems with trace nutrient def in new AP systems since mature systems probably have more mineralization of the solids left behind in the grow beds taking care of many of the problems.

I have needed to add Iron and Potassium for my system though I think most of my Iron problems are due to high pH. I'm thinking I'd like to try some green sand in my system to see if it can take care of both of those main nutrient problems.

Do remember that nutrient problems in plants are often caused by pH or too much/too little of other nutrients.

For the Aussie brigade this may be worth a shot,,,
http://www.plantdoctor.com.au/fertiliser.htm

Just a bit suss on fertilisers mixed with fish, so need to check it out before use...this is the one I use and what it contains:

MinPlus