Backyard Aquaponics
A place to discuss aquaponics

My tomatoes are not responding as well as I believe they should. I have a 700l fish tank and a 400l sump tank. I have only recently introduced a dozen jade perch fingerlings although I have had about 30 or so smaller creek fish for several months. I have been adding about two cap fulls of Charlie Carp every few days and a cap full of season every week. I think this is providing enough nitrogen as my green leafy plants seem to go well. Not so sure about the trace elements though?


My water chemistry is pretty stable with zero ammonia and nitrite and nitrate being used up in a day or so, so I think my nitrosomas and nitrobacter are doing their job. The only thing I have noticed lately is that my pH is up around 7.2.

As can be seen in the accompanying photos, new foliage on the tomato plants stats out OK but older foliage looks a bit blackish. On more established plants, a lot of older, lower growth yellows and dies off. The fruit itself takes a long time to show colour and then only gets to an orange on the plant, never a rich red. Even taking them from the vine and placing them with shop bought ripe tomatoes results in them ripening but only to an orange-red mottled stage.

They are grown in tropical Australia in full sun but it is winter so the sun is not too harsh. I have recently added some shade to see if this helps though. I have also added some chelated iron but I would have thought there would be enough in the Seasol. I do grow a fair bit of bok choy so would this be removing the iron in solution?

Does anyone have any other ideas?

but it is winter so the sun is not too harsh. I have recently added some shade to see if this helps though.

if it was a heat issue they would be ripening too quick (at least issue in our dry heat anyway).
suspect you still need full sun to get vine ripening.

Nitrogen from FT only promotes green growth. Flowers and fruit depend on potasium and other nutes. Do you supplement ?
Charlie Carp is a bit like seasol? In most AP have to use seasol and power-feed combined.
After reading another thread I am trialling blood&bone plus (B&B with added potash) and sprinkling that on surface of bed and hand watering in - but my AP tomatoes have not started yet, couple weeks to go.

The only supplement I use is a spray with epson salts solution. It is supposed to assist in flower and fruit formation. The flowers and fruiting seem to be happening pretty well. It's just that the fruit take forever to grow and ripen (6-8 weeks after flowering) and even then, do not get that nice rich red colour.

I have that issue at present with some carry over tomatoes but here in Perth that is simply due to it being too cool at moment. eg. getting some cherry tomatoes ripening in full sun against a wall but full-size tomatoes stay green.
3-4 weeks off and temps here in Perth will be fine. (hence just still mainly at seedling raising stage)

sorry cannot be more helpful.

How much sunlight are they getting?

They seem to be slightly leggy, not bad, but longer than they should be.

Also, what type of tommies are they? Not all varieties are created equally, some will fruit better than others, some will take longer to ripen.

I tried some seeds from a Coles shop bought tom but they came out pretty crappy. I pulled them out and now I only have about a dozen Romas and a dozen cherry toms under way. They all seem to be fruiting quite early for small plants so we'll see how they go now that I have added some chelated iron. They were in full NQ winter sun which is starting to get a bit warm in the middle of the day so I have added some shade in the last week. However, this does not look like a burning effect. Much more like a trace element / chemical deficiency or overdose. I just want lush green plants and beautiful sweet, rich red tommies. Not too much to ask for is it?

I'd remove your shade cloth. You might need it in the middle of summer, but not in winter. It could be causing your problems. Have a look at Andy's thread:
viewtopic.php?f=18&t=16235&hilit=shade&start=750#p485284

He was having issues with lack of light from too thick shade cloth. Removing it made them fruit well (after the shock).

Seeds taken from store bought tomatoes won't be true to type, they'll be grown on a grafted plant, and normally will grow different tomatoes than you want

You're better off searching through ebay, or I can send you some tomato seeds if you want?

CC is basically powdered fish, which breaks down to provide an ammonia source. Now that you have fish I wouldn't add any more. Seasol will provide trace elements.

Heavy feeding plants in a new system will struggle, its very common. But the cooler night temps of winter won't be helping.