Hello my fellow aquaponians

Here is a rundown of my very basic system, that I have been running for a little over a year.

Parts: 1 Fish tank, 1 pump 500 liters p/h, 2 grow beds, 1 tank heater, 1 air pump and stone, some 12 and 13 mm water tubing, clay balls, river stones and 2 gravel guards. (see? very simple.)

Setup: My fish tank (2 ft) sits on a workbench in my garage, which pumps the water up through the window and into my top grow bed (both are baby baths filled with clay balls), that then drains to the second grow bed, which is then drained back into the tank by going through the window again and thus completing the cycle.

Notes:

This is a continuous flow system at this stage.

I am currently growing tomatoes and strawberries (tomatoes have fruited and taste great, strawberries are just starting to fruit).

I have guppies and a bristle-nose catfish in this tank (catfish to help with keeping tank clean, I have bred my guppies).

My gravel guards are DIY, one was the cylinder of a filter in a bag less vacuum, the other is a 2 liter plastic bottle, the middle cut out and punctured holes in it to allow free flow of water, both have worked fine so far.

Before I started using the baby baths, I used two kitty litter trays, which grew tomatoes fine, just doesn't allow a lot of space.

Questions:

I have placed my air stone near my pump, I assume this will help the pump carry more oxygen to the plants, is this correct?

Are there any obvious flaws with this system? (I would assume not since it has been stable for a year)

Are there any simple/cheap things I can do to improve this system? (I am generally tight on cash, so try to go the DIY way as much as possible)

I have a live plant in my fish tank, does this have any effect on the plants in the grow bed? (positive or negative)

I have other fish tanks not yet setup to aquaponic systems, I would assume that the water I get out of these tanks when changing the water, would be much better for the system than tap water, with all that fish poo and whatnot in it, poured into the grow bed system to filter a bit before getting to the tank, is this correct? or should i use tap water?

Thank you all for your time

Jay the Druid from Aus