I have a 40 gallon with a 6 inch reddevil cichlid in it by itself.For filtration im got two aqua clear 200 filters.Should i get one more filter like a magnum 250 or what.
if you put one filter at either end of the tank then i would say that that would be enough, since it would total 400 gph, or the filters (combined) filter the water 10 times per hour
