Backyard Aquaponics
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pH 6.5, NO3 50. I've recently added iron and the leaves have greened up. I also added potassium to help with fruiting plants. But new leaves aren't growing to full size, not sure why? Plenty of nitrate, silver beet, basil and lettuce are stunted although otherwise healthy. Spring onion new leaves are crinkly, like they too are stunted. Has anyone experienced this?

I was having a similar problem as well. but my nitrates were > 100. I was getting stem rots and leaf tip burns together with dead spots on my lettuce leaf. I found out I had actually had two problems. one being my nitrates (NO3-) were at too elevated levels. Secondly it was also a potassium deficiency sign as well. so I had to make so drastic solutions. first of all to contract the high nitrates level.. look for a fish food lower in protein like say around 16 to 18% protein. I was using 33% protein content before and for nothing I couldn't control my nitrates levels. Secondly create control anaerobic areas in your system to convert some of the nitrates back into nitrogen gas. I usually just leave back a level of waste in my swirl filter (clarifier). best to keep your nitrates level around 30 max.

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Ive had nitrate levels up to and in excess 600 without issues, you either need to plant more plants, add grow beds or reduce fish numbers/feed levels..

Can you post some pics of the affected plants?

30 ppm I meant to say. and finally potassium. this is where the complications comes. u say your ph is around 6.5. but do u have a conductivity meter..? well my system runs like around 0.5 miliSiemens. a good rule of thumb is that your potassium level should be atleast 2 times greater than your nitrates. calcium and phosphate can be the same or a bit lower than the level of your nitrates that is around 25 to 30 ppm. same for sulphur. the problem is to truely kno the levels of minerals in your water stream, water analysis via a lab is needed. if this is available to u all well and good. u can supplement accordingly.. if u don't well here is where the fun comes to play. we will definitely have to approximate and hence we need atleast a conductivity meter. let me kno your conductivity and I'll guide u according at that time

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Thanks cookie you hit the nail. I am having leaf burn and spots. My curcubits germinate then wither and die. I don't have a potentiometer, but I have access to a biochemistry lab. Unfortunately the chemistries are calibrated to a blood serum base but I wonder if I were to analyse how accurate the results would be, probably sufficient. Will bring in some water tonight to work.

Might need a little help modifying the results to the right indicies.

I can measure K, Ca, phos (as phosphate), bicarb (would that determine total bicarbonate?)

Sounds like you need to swap your fish feed...

Thanks earthbound, just about to pull my trout and sub with SP so can go a lower protein. If the problem is the nitrates its no problem cause I can use the water on my other garden and refil with dam water. Just don't know what the actual problem is.

Sounds like deficiencies to me, but then it could also be a combination of things including disease or bacterial issues on your plants... Use skretting feed, we use this in all our systems and rarely if ever need to worry about any deficiencies or plant problems...

I'm pretty sure I use skretting.

Just had a good look at me media on a fill cycle. There's millions of little brown bugs about 1mm long, no wings. I doubt I'd be able to take a photo.

Hmmm don't feel like I'm having much luck latey with this AP thing .

Sounds like it might be fungus gnats...

Water fleas perhaps? After every decent rain I find heaps of them in the chook water bowls, puddles etc. None in my AP so far though.

I think earthbound may have picked my previously unidentified bug infestation. I googled fungus gnat and images look similar to the prob I have.

Someone (can't recall who sorry) in my bug infestation post correctly suggested I use Bacillus thuringiensis isrealensis .

No idea where I can get this but will ask elders.

Any other tips on controlling this infestation?

lol you are one lucky soul to have access to to biochemistry lab.. I'm a bit jealous actually.. bit yea let me now your results for K, PO4, and Ca and I'll guide u through to helping out the situation

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