I was wondering if I really needed a filter in my (soon to be heavily) planted 29g. I currently have an aquaclear 20 on it, but its so small I dont think it really makes a difference, so would it be possible to just us eone of my extra MJ PH's instead? right now all I have is some swordtails in it, though tomorrow I'll be getting more fish (some schoolers) and some plants.