Backyard Aquaponics
A place to discuss aquaponics

Thats great, its like a clown car.
maybe try finding a small storage container and putting some holes in that, weight it down.
I dont know how big your tank is, but you pretty much hit the limit as far as pipe goes.

Not always practical, but Ive used clean driftwood from the beach or local river in the past. Perhaps consider adding a few water plants. You can grow them in plastic pots in gravel (no soil) which also weighs them down keeping them on the bottom.

Try create a natural environment for your fish?

I [and my wife!] would love to put tons of stuff in there but I thought that the wisdom was that solids would be trapped in there vs. getting circulated and filtered/used up? Am I overthinking it?

There's a few schools of thought on that point.

The photo above was of a lightly stocked system where the focus was a small number of ornamental fish. Yes I used gravel on the floor of the tank, which some may see as a no-no. Yes, if badly done, gravel on the base could create anearobic zones.

In a heavily stocked system you will probably want to keep the fish tank floor as free as possible to avoid trapping solids. If you are after maximum amount of fish in smallest amount of space etc that is. But then it sort of can become like the fish version of battery hen farming where the fish have a pretty boring life

Personally, I think there's a balance.. I try to create as much a natural environment for my fish as possible, for their quality of life.

I haven't had any ammonia/waste buildup issues in the tanks that I have used gravel in. But I keep a good water turnover, have circular tanks (or ends of the tanks semi-circular like in above photo) and create a slight whirlpool effect where the waste accumulates on the floor in the middle of the tank where I place the pump. I also run airstones so there is always ample aeration.

Also I've found goldfish and Koi are excellent at cleaning the tank bottom. They love to suck up stuff in between the pebbles, and when they do that it re-suspends into the water column and the pump/growbed handles it.

Think of it this way - some of the most healthy dams and ponds still have a buildup of biological sludge at the bottom. I worked for a gardener for a customer with a small outdoor pond very heavily stocked with Koi where there was about 5 years of buildup sludge on the bottom (mainly dead leaves, fish crap etc), about 200mm thick. I initially gave the fish a life expectancy of a couple of months, but the pond went on like that for years, with happy fish. It changed my thinking. The key I believe is adequate filtration and water turnover.

Most people keep thier tanks bare for solids removal.
Some people have added beds to existing ponds.
It all works.
The pond plants will use nutes though, so if you want heaps of veges, then you may need to have a few less so your water plants can live.

Lots more good info, thanks! I'm going to the pond/fish/aquarium store and see what i can do for these guys. They definitely like to play - there's a few balls of hydrocorn that fell in and they're always messing with them.