New gardener - plant selection, fish sources, food stuff

[PJ]

Greetings. New to aquaponics and happy to finally introduce myself.  Of course, there are some questions buried in the post if someone is obliged to comment.  

2 months ago I started fishless cycling.  Took forever, but finally happened.  As it continues to grow and change, I find that I'm obsessed.

A few specs on the system:
-55 gal fish tank
-River rock 
-Flood and drain
-Grow bed 3ft x 2ft x 8in deep
-8 bulb t5 lighting
-27 tropical community fish
-Lettuce, basil, radish, broccoli, kohlrabi, bush beans, tomato 

Plants are growing, but not so well. They stalled for a while and leaves started looking burned and turned crispy.  Light was close to the plants, so I moved it to 12 in., but t5's shouldn't cause a heat issue in my opinion.  I gathered that PH was too low (5 or lower) and might have caused nutrient lockout. Took some steps to raise PH, and now it's 6.4 - 6.8. Afraid to raise it further for fear it will get out of control. PH baffles me.  So much contradictory information online.  I bought calcium carbonate on one recommendation; now i'm reading carbonates are not good.  Hesitant to make any other PH moves.  Anyway, plants are doing better now.  I have happily harvested radish and basil, but the lettuce is still browning and tomato leaves are still curled upward and it defoliated much of its lower stem. 

Am I growing the wrong plants in a starter system? I think I may have made some wrong choices and/or planted too densely. I get the sense that the heavy rooting plants are choking out the others.  Probably a mix of issues.  Any thoughts or observations?

About fish I should say I did not plan to build and keep a long term community tank, but could not find a tilapia source in my area (Johnstown, Latrobe, and Indiana PA nearby).  OK, and I was eager to make poo. So now I have some cheap tropicals and feel a bit stuck with my selection.  In such a relatively small tank, does it even make sense to stock fish to harvest?  With my system, what would you stock, and where would you purchase?

Lastly, I'm sure my TetraMin flakes are filled with noxious crud a human should not indirectly ingest. What semi-healthy options would you feed tetra, barbs, and cory cats? Is there a recommended organic food source for tropicals?  Or scrap it and start with different fish?

So there it is. Freshman mistakes and all. Thanks in advance for any pointers, and thanks all the information thus far.  I wouldn't have been inspired to explore the hobby if it wasn't for this great community and wealth of information.  PJ

[coty]

Im still new but i am growing duckweed and feeding that to my fish. I am also using random tropical fish in my system. Mainly plattys and mollies but they will eat the duckweed. I have also been reading about growing wheat grass and if you blend it up a little the fish will eat that too! Eventually i would also like tillapia or catfish.

[Jonathan Kadish NYC AA Chair]

The best plants to grow when your system is new are leafy greens as your system is not yet nutrient rich. I did tomatoes after about 5 months and had success. PH a neutral 7 is the best to maintain and the two main things most aquapons buffer (raise ph) with are calcium carbonate (egg shells) and potassium bi-carbonate which you can find on ebay. If your ph gets too low (below 6) you run the risk of a system crash where all your bacteria and fish will die. If your ph gets too high (8+ range) you could start to see certain minerals become unavailable (lockout) to your plants.

An Aquaponic system will produce more in it's 2nd year than it does in the first so be patient.

[PJ]

Thanks for the responses.  It's good to know production will increase as the system matures.  I'll maybe pull some plants and repopulate with leafy greens until then.  I need patience for sure.  Regarding PH, I tried eggshells but noticed a sulfur odor and figured I didn't prepare correctly (though I had boiled and baked the shells). I tested again and it's at a stable 6.4, but I realize i'll need to supplement soon; i'll try the potassium bi-carbonate.

So far my fish are not interested in greens that I've tried, but I admit I haven't given it a fair chance.  I'll have to test some duckweed and see what happens.