Quote Originally Posted by bcotton
When tomatoes are ready to fruit they start using a lot less nitrates and a lot more phosphorus. Aquaponics is notoriously low in phosphates. You can add a supplement or what I do is just limit the number of fruiting plants in my system.

This is just a guess. If you can swing a picture there's guys on the forum that can tell you exactly what the issue is.

brian
Sounds like a lot is expected from this guy. No pressure!