I have had a 10 gallon tank for almost a year, and have not been able to stabilize it. Right now, the problem is green water. I've tested the water, and the ph, nitrite, nitrate and ammonia levels are all fine. I took out all the gravel, and only have marbles in it. I replace about 20% of the water every week, but the water is very green. The algae doesn't seem to grow on the walls as much as in the water itself. I have no plants. I currently have 3 neon tetras in the tank, and one algae eater - not sure of the name since my husband just picked him up. I'm ready to replace all the water in the tank, but don't want to risk these fish. Any advice/help would be greatly appreciated.