Backyard Aquaponics
A place to discuss aquaponics

Hiya! Haven't been on in a while, but we seem to be having some plant growth difficulties.

I'm part of a school aquaponics program, and we've been having some nice growth with a lot of what we've planted (okra, lettuce, broccoli, and microgreens have all been doing quite well). However, we also have two or three varieties of peppers as well as some tomatoes that are growing and flowering, but not producing fruit.

Levels in both systems are as follows

Peppers:
pH: 6.5
Ammonia: 0.5ppm
Nitrite: ~0ppm
Nitrate: 40ppm

Tomatoes:
pH: 7.6
Ammonia: 0.5ppm
Nitrite: ~0ppm
Nitrate: 40ppm

We've also been putting phosphate into the plant beds, but it doesn't seem to be having much of an impact on growth. Our fish are doing very well and are eating a lot (and thus producing a lot of waste), so there's definitely enough nutrients for the plants.

What kind of phosphate?

Sounds like the tomatoes and peppers are growing and flowering so are the flowers being pollinated? You're probably still growing inside at this time of year so I have to ask if you are pollinating the flowers or do you have some pollinators in your growing area. If not then you'll have to do this manually. There may be some other contributing factors like temperature and humidity.

If you're not getting much growth and you're only seeing this in the tomatoes and peppers then it's probably because the water temp is low. Both are warm weather crops. I usually think of Okra as a warm weather crop as well but I'm not certain where it's growth picks up.

We keep everything inside year-round, so we have been hand pollinating using paint brushes. It stays pretty close to around 80 degrees with consistent humidity.



We're using rock phosphate with available phosphoric acid guaranteed at 3%, applied directly to the plant beds to protect the pumps.

We keep everything inside year-round, so we have been hand pollinating using paint brushes.

So you are wasting time and effort, try a battery powered toothbrush and you only have to touch the top of the cluster. Or if you are growing on wires, vibrating them will affect the whole vine.

It stays pretty close to around 80 degrees with consistent humidity.

Try reducing to 70 degrees during the day with 70% Humidity. You are pretty much at the top of the range for good pollination


We're using rock phosphate with available phosphoric acid guaranteed at 3%,

Do you have any literature, or product name for what your using.



applied directly to the plant beds to protect the pumps.

I think it's probably a temperature issue at least for the tomatoes. You'd be getting some pollination no matter what method you use and there's no point in buying an electric toothbrush other than just to save some time since you have plenty of help and don't need every tomato to take anyway. Take a look at the minimum and maximum temps of the air. Air temps need to drop below 75 at night but daytime temps up to 90 are still OK depending on variety you choose. It wouldn't surprise me if the peppers are having similar problems since they're in the same family.

I know the humidity wasn't specified but it should be below 80%.