I have been wondering do you some how pre filter the water before it enters the sand filter? Do you have some type of inline mechanical filtration? Or does a sand filter do it all?
OOOOHHH ok, a pool filter. Right on. I would most definitely have some sort of mechanical filtration prior to running tank water into a pool filter. Probably a sponge or sock or some sort.
You would need some form of mech filtration to breakdown bigger particles before it enters the sand filter.
What i did in my sump was take the pump out of the sand filter and plumb the return from my sump pump into the sand filter intake.
So water comes through my sump, then sand filter and back into the tank. I find that it polishes the water pretty well and with 15kgs of zeolite it removes any ammonia that didnt get chomped passing through the sump.
I actually like your idea foldem, this way I can slowly remove the bio media from my sump.
I liked the idea of a sand filter so I could get rid of my sump. The only reason I use a sump over canister is so I can have constant water level in my tank, and easily cleaned. I am setting up a drip system so I will always have the same volume of tank water, and I am pretty sure you just back flush a sand filter.
There is a differance between a fludized sand filter and a sand filter (sand bed filter)
As i understand it A fludized sand filter has sand that is churnded up by water making it constantly moving and rubbing the sand grains. Bacteria grow on the sand making for a high surface area bio filter without low oxygen dead zones.
A sand bed filter the sand is some what packed and water is pushed through it trapping fine particales in the sand. When needed you move the valve and back wash the stuff out into a drain line, the sand is mixed up to release the debri. Then it is packed back down with a turn of the valve and it mech filters.
I mention this because you said you want to slowly remove bio media and your sump. The fludized bed filter needs a pre filter the sand bed is a mech filter.
I am not talking about a fbf. I am talking about a sand filter like the one in the picture above; I don't like fbf. as far as the sand filter being mech this might be true but all mech filters are also bio filters as bio grows on everything. the sand will grow bb on it and work as a bio filter as well. In the larger public aquariums they dont use canisters or sump or trickle towers.
You might look at spin on filter housings.
Either cartridge based or micron rated screens can trap alot of debris in a small, easily serviced space and not cost a fortune.