Probably a super stupid question and should go in the nooby section but how often should one clean their tanks filter? Like the HOB filters. Cause I have a sponge filter and I clean it every few months but just kinda squeezing it with my HOB filter media swish. But I don't really know when or how to clean the inside of the HOB filter, or even if I should. Well, I mean, I should right? Do I just take a sponge and kinda wipe the gunk out? How often should I do it? It doesn't really look that bad inside so... :/ Just a q.