Nitrates stuck at 20-25 PPM

[Dan_P]

I started up a new tank, its about 1.5 months old and fully cycled. After I finished cycling I did a 75% water change, my nitrates wont drop below 20-25PPM. I've done 3 40% water changes since and nitrates don't seem to wanna move down at all.I have 2 clowns and 1 yasha goby, it makes zero sense! It's a 20 nuvo. I'm not overfeeding at all either. My rodi water comes out as 0 nitrates so its not my water. I'm using salifert but the api test also shows the same numbers so its not a testing issue. Not sure what to do really. I cycled with dry rock

When 3-40% water changes are performed and there is no change in nitrate concentration, something is wrong.

Let’s start with testing error. What is the nitrite concentration?

 

[Randy Holmes-Farley]

Carbon dosing with vodka or vinegar?

Vodka initially, but it spurred cyano so I switched to and stayed with vinegar.