Growing Peppers and tomatoes- need some help.

[Art]

I have a small indoor aquaponic system for about 6 months now.  I am having trouble getting green peppers and tomatoes to start.  The plants look great but no vegetables/fruit.  Basil looks good, some lettuce, but no green pepper or tomatoes.  What am I doing wrong?

System information:

2 grow beds - soon to be 3

180 gallon fish tank

32 tilapia fish of various sizes

PH 6.4-6.6

Ammonia:  <0.25ppm

Nitrate:  <0.25pp,

Nitrates:  0 ppm

Fan:  on for about 1 hour a day - also shake the plants every few days.

Add iron:  1/2 to 1 tsp every 2 weeks.

thanks for your help.

[Art]

that is the problem - no fruit at all.  I added a small orange and I will add a banana.  I have the grow beds filled with clay pebbles and have marble rock in my sump tank to help stabilize the PH.  so not having enough potassium is a possible cause.  I ordered liquid potassium and have increased my feed.  I am getting a 24 feeder to feed the fish at lunch time.  so this will increase the feeding to 3 times a day.

Thanks for all the help.  I have to wait a few more weeks to see if this is helping or not.