So I got a 29 gallon tank about 2 weeks ago, and well I got fish before it even cycled. Beginners mistake. But I have been testing it every day, and doing water changes when ammonia or nitrites get high. But I tested it today, and ammonia is at 0, and nitrite is almost at 0, but I noticed how my filter cartridge has a Bunch of brown algae on it, and some water is coming over the filter carriage, like overflowing. But i Know I am not soposed to change the filter while still cycling, but its overflowing? So should I change it? Or keep it in?