Sounds like you have a very sunny spot. One way to control green water is by using a product called pond tint. It will shade it so to speak thus cutting back the green growth.bbnp said:HI thanks for the reply. It is a little porous.
Dadio do you use a uv sterilizer or something? I only use my filter and a waterfall but the water is green. A uv sterilizer is a bit too expensive for me, what are other ways to make the water clear?