I have a 55 gallon aquarium with community fish in it. I have a Penguin Biowheel 330 filter and a heater. I keep my temp at about 78 Fahrenheit. I want to know what works for all of you aquarists with lots of experience. I have hard water, but right now my PH is at about 6.2 although my water is typically at a PH of about 8. I only keep up with the PH and ammonia levels. Right now there is no ammonia in my tank, although for some reason, it did spike up high about a month ago, although I have had my aquarium for about a year. How often do you do water changes? What chemicals do you add? I don't have any plants. I do have air bubbles. Right now my fish seem to be sluggish. They are eating fine, but they don't seem to be as energetic as they used to be.