So I am trying to see if anyone has run into the situation I am in and what they did about it. I run an algae scrubber on my mixed reef tank and i have done so for about 4 years. My nitrates have always been undetectable....even when having gone months without water changes. Suddenly I have had a nitrate spike. For reasons unknown to me, (nothing changed that I know of) they went from 0ppm to 15ppm. I did notice that my scrubber wasnt growing algae very well a couple of weeks back but seems to be doing fine now. My current thought is that nitrates built up when the scrubber wasnt growing but thats just one of a million possibilities. Soooo long story a little longer, has anyone run into anything like this and if so, what did you do?