I have a marineland 56 gallon column tank . It is a dirt planted tank with 13 plants of varying lengths (will be adding more soon), for filtration I have a Fluval 406, I do a 40% wc every week. In my tank I have 4 angels, 3 Gourami's, 6 Black Neon Tetra's, 3 dwarf pleco's (I forgot the actually name) and a dwarf upside down catfish. I know you can't have too much filtration unless it creates to much water turbulence. However, I've been thinking about adding a sponge filter or another filter that's not (HOB, wife hates the noise of them) My question are: How much filtration do plants actually do? I know some people have a tank so planted that filtration is not needed. Is adding a extra filter a luxury or a necessity? If its a necessity and you didn't use a HOB what would you use? Thanks is advance.