My friend has a 55 gallon tank with a red ear slider turtle. It has two of the penguin filters with biowheels and the tank is only filled about 2/3s of the way up so the filters have to draw water up and it falls back into the tank. He doesn't do water changes and has never replaced the mechanical filtration cartridges. He even has bright heating lamps for the turtle and only adds water when the level falls below the intake of the filters. The tank has been running for just under a year and there isn't any algae. How is this possible?
) and that's killing off the algae