Is this the same tank as the temp problem in the other thread? If it is, my advice is to slow down and stop messing with things.

The fine sand will eventually gain some biomass and settle. I agree the fine stuff isn't the way to go especially if you have a lot of flow.

While Miztanks may be right, I think by the time that happens you will have enough biomass on the sand to keep it from stirring up as easily.

Get what you can with a canister filter and go easy on the changes for awhile.