Aquaponic Gardening

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Hi everyone! I need your help. I have run my raft system for about 2 weeks and now some of my tomato cucumber and lettuce leaves turn from green to yellow. Is it right saying that my plants are having iron deficiency? To solve this problem some documents recommend using Iron chelate. Unfortunately, iron chelate is not available in my country ( Cambodia). Anyway, I've found another product which is mainly composed of Zine (a type of metal). Can zine help me solve this problem. Can it replace iron chelate or not?

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My Nitrite is about 0.  My Nitrates are under 20.  pH is 6.8.  I was thinking that the older part of the plants were in fact nearing the end of their time, but it is beginning to effect the new growth as well as some smaller, younger plants and cuttings.

TCLynx said:
You say your levels are what they should be?  What does that mean?  What is your Nitrate level?  Older leaves yellowing could be a sign of nitrogen deficiency but I've noticed that tomato plants do tend to sacrifice their older leaves in favor of new growth even in systems with plenty of nitrogen. 

Allisyn Wood said:
My system has been up and running with fish for a few months now.  My levels are where they should be.  My older tomato leaves are turning yellow first. Started about a week ago.  Suggestions? 

Ammonia and nitrite should indeed both be 0.  Nitrates under 20 seems fine to me.  pH of 6.8 is also really good.


Have you ever given a dose of seaweed extract to the system?  New systems often suffer from various minor deficiencies and seaweed extract can address many of them and Maxicrop with Iron can even help with the Iron issues too.

I never did add maxicrop.  Is it safe once the fish are in? Where might I find it? Online only?

As long as you do the Maxicrop original or Maxicrop with Iron it is safe for fish (avoid anything with added fish emulsion or NPK numbers greater than 0.1-0-1)


I haven't had much luck finding it locally here except at the BWI distributor so you might have an easier time getting it online.  Sylvia sells it if you go to the shop tab up top.

How much do you recommend adding to a system of 100 gallons I just got a bottle of the Maxicrop plus iron  and I'm not sure how much to add?


Something between a spoonful to an ounce.  For a 100 gallon system a shot or a splash will be plenty and still enough to probably turn your water dark for several days.

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