I had a hot magnum filter on my tank but it seemed like I was always fighting with it to stop blowing bubbles in the tank so I switched to a filstar xp2 filter anyway I keeped the magnum and it has micron filter that came with it and I was told its for scrubing the water I,m not sure what this means or how often I might need to do it. I guess I should know it by now but you know"the only????" and I know that I,ll get an anwser here that I can trust Thanx, Dave E
