The only way I could imagine keeping the water clean enough with out slaving over it is to make it part of a larger system. Like cut a hole in the back, put some fine mesh over the hole, and have the hole over the sump of a larger system. Then make the the water from the main tank go to the 3 gallon, which in turn flows in to the sump, which has a pump returning water, etc.....or you could save yourself a boatload of time and effort and upgrade to a five gallon and keep a common species like N. Wennerae....or even better, a ten gallon.