I have had a 55 gallon tank set up for about two years now. I only have about 5 fish in it and each are about 4 inches. so its not over populated. I have 4 filters going to it. And I have a UV algae killer hooked up to it as well. My question is. no matter what i do to it and how often i clean it. It ALWAYS has a light yellowish-green color to the water... How do I get rid of it?!