I'd use emergents, like peace lilies etc, that require low light, maybe window light can be done to save $ on electric. Basically just a simple flow through in a sump packed with those Hydroclay balls hydroponic places sell(good bio media also).
I would also use a large hard plumbed drain and refill directly on the tank.
Turn a valve: drains tank via a 2" PVC, or 1" etc. Refill use 1/2" or 3/4" and add dechloro or run through a carbon pre filter.
Do that 2-8 X a month at 1/3-1/2 the tank volume.
Send waste water to landscape plants, soil, lawn etc outside etc
Once the plants get going well, they should keep the waste down and you can reduce the water changes. Aklso, have very high flow in the main tank with those lazy fish. They need good current, exercise, they will live longer and eat better/better behavior.
The high current also adds more O2 and stirs up the waste, looks nice.
Low pressure high volume is what you want, eg a sure flow kit on a Maxi jet, 2000gph for a few$, add 2-4 of those in addition to a decent filter.
BTW, the energy is much less for these types of pumps vs a high pressure return pump for filters(about 5-10%).
That will save you a lot more $.
Regards,
Tom Barr
