Its also a good idea to get a extra filter or bigger filter than what the tank will normally need. For example on my 30 gallon i have a 60 gallon size filter. For both my large tanks i have double what i would normally use, it helps to keep the water quality good when keeping larger numbers of fish as we often do with african cichlids. I also skip normal feedings at least once a week sometimes two days (not in a row) it does not hurt the fish and on those days i noticed they really dig the substrate and around the rocks looking for food, this helps to keep the tank cleaner too.