50% water change and still 20ppm nitrates

[o.c.d.]

Po4 is one of the triggers for cyno.

[Milad]

now that i think about it
this problem is familar

When i first setup the tank, i had the same symptoms, algea growing fast on the glass

I added rowphos and it stopped

I removed rowaphos recently and it started

So maybe Im doing this wrong, I should start zeozyme and zeobac again so the bacteria can eat away at the phosphates?

[ottoman]

I think algae also feed on PO4. Better to test your PO4 as well as Nitrate. I don't use zeozyme or zeobak, but I dose cv and snow. Use only 1/4 or 1/3 as noted on the bottle. When I first started cv and snow, I followed the instructions on the bottle, I have algae problem.