Red algae

[Reef Pilot]

Even N03 of 20 is not really high, unless you have SPS corals. Fish certainly don't mind. But you should get a better test kit.

What do you use for P04? Many of the cheaper ones do not measure accurately at the low end. Salifert or a Hanna LR checker work well. I used to think I had no phosphates or very low until I got a Hanna Phosphate checker.

Having said all that, one of my tanks used to have high nitrates (40+ consistently) and high phosphates (over 1.0), but I still did not have a cyano problem because of my MB7 dosing. It adds beneficial bacteria to your system which out competes cyano.

You'd be better off changing 10g of water every 2 weeks.