Current tank setup is 20 gallons, 3 Ottos, a Weather Loach, 6 Tiger Barbs and 6 Zebra Danios. I have some Water Sprite floating and some Java Moss anchored on the bottom. I have not had any problems with my current filter, the Penguin 125, but it is starting to have flow problems. I've cleaned it out real good but there's not enough force to drive the biowheel when I have the filter cartridge in place which is not good. Anyways, I am going to get either an Emperor 280 or 400. The 280 should be fine, but it's only $5 more for the 400. Would that be way too much filter for a 20 gallon? Would it be better to go with the 280 and also keep the Penguin going so it circulates the water a bit better and just take the filter cartridge out and just have the biowheel going?