Help with Cyano

[eyedoc]

I have a purple film on the sand and rocks. It is localized but I want to kill it. I hear there is a product that is made for this.
Is there a treatment that will kill this without killing helpful bacteria?

[mg426]

Chemi clean is one that is supposed to work, I have heard people who have said that it will harm Bacteria. Try increasing flow in your system and ensuring that Po4 & nitrate are in check.

[deepblueat2814]

I just take the rocks and brush it with a toothbrush. I think it is alage and the problem is nutrient in your water.