Glad to hear you got a test kit. That's going to help a lot.

You might try this gigaguy......(hope the drawing will help this to make sense)
Get another large tub....use it for a sump tank. Bury it in the ground ( a few inches sticking up). You can have a pump actually 'in' the sump or... pump 'from' the sump....your choice.
You will be pumping 'clean' water from the sump... to the FT. The fish tank will overflow, through the slo-drain....into the (3) grow beds. The GB's, will then drain the water back to the sump.
This will give you more water to work with....slower to heat in the summer. The fish will be happier because their water level will remain 'constant' in the fist tank. Hopefully, more oxygen too.

Look at the picture of the slo-drain.....should make sense. Water naturally seeks it's own heighth. As you pump 'more' water into the fish tank, the water will flow 'up' the pipe and exit the tank. The reason the slo-drain goes to the bottom, is to help pick up 'solids' (fish pooh) and carry them to the GB's.
People add red wigglers to the GB's to help break down the 'solids'.

Add some kind of insulation around your fish tank (styrofoam) and the GB's too, in order to regulate your temps.

Here's a 'hand' drawing... ...hope it gives you an idea.
I only drew 1 grow bed, I know you have more, was easier to draw. You may need to put some kind of blocks under your grow beds, IF, you need some heighth for the drain pipe to get to the sump.

This type of a set up is called..CHIFT PIST...Constant Heighth In Fish Tank....Pump In Sump Tank