i'm in a process of re-scaping my 196 G tank. I'm using UGF and Eheim 2250 canister filter. I put gravel as the bottom layer, then clay before my top gravel. It's been 4 days and the water hasn't been cleared yet. I already do water change at least 40% for 4 times. What should i do ? Is it possible because of the UGF ? thanks