I inherited a 55 gallon show tank and it came with a Tetratec PF300. Apparently they're no longer in production, but here's a picture at least: I read in a different thread that your water should cycle 10 times per hour, so for a 55 gallon tank, should I have a filter that cycles 550 gallons per hour? This filter only does 300, but it was used with success for many years. It says it is rated for up to 60 gallons. I also have two air stones to aid with aeration/surface agitation. A quick search of filters that cycle 250 GPH turns up filters that are about $50. Unfortunately I'm not really in the financial position to be purchasing extra, possibly unnecessary filters. My questions are: 1. How necessary do you think it is that I increase the filtration? Currently there is a male betta and a female BN pleco; final stocking is: one angelfish, possibly a DG, 8 neon tetras, 6 platys, 6 cory cats, a BN pleco, a bamboo shrimp, and a nerite snail or two. 2. If you feel that more filtration is needed, is there anything I can do besides spending $50 on another filter? Thanks! Edit: Upon further research, it seems that filters that cycle 250 GPH are rated for 55 gallons! It seems almost silly to have two filters rated for the volume of the tank. Maybe I misread, and that suggestion was for particularly messy fish?