I am preparing to buy a 50 lb. bag of pool filter sand and was wanting to get some black sand to mix with it from Petco/Petsmart, this will be for a 55 gallon tank. Was wanting to know if 1 5 lb. bag would be enough black sand to make a difference or should I get 2 5 lb. bags? Also I want to possibly put mopani driftwood into the tank, would this be O.K. or would this not be such a good idea? Last of all what type of filtration do I need to use, I have alot of sponge filters and I have an AC 110 and AC 70 for filtration, I know the sponge filters would be good to keep from sucking up babies, should I put a sponge filter over each filter intake or should I use sponge filters and if so how many for the 55 gal.