i have a 50 gallon piranha tank,in it are 14 baby red bellys. the filter is a magnum 350. i want to clean out the filter, but before i do.....all my good bacteria..(cant spell) is in the 40lbs of sand rite??? will it hurt to clead out the filter??? also is that a good filter for a 55 gal? i also have a fluval 305,and a fluval 304 i could use if they are better.. thanks for your time