I appreciate the help. I replied to your post last night. It did not get this way in my tank. My tank is a biocube 29 with bioballs removed. Media basket w/filter floss+pura pad on top, purigen in mid, and cpe on bottom shelf. Fuge basket with chaeto. Heater In 3rd chamber, with maxi-jet 1200. Loc-line y on return with two return nozzles, one pointed up to the surface and toward the front left corner, the other pointed down the back behind my rock. I have a 250gph powerhead on the intake side, halfway down pointed up to the surface and facing the front. There is good flow in the tank, but not too much where it will blow the sand around. I have a 36w 10000k bulb in the hood at the front, a 36w actinic in the middle, and a fixture with 20x1watt LEDs over the rear. Temps stay around 79. Params are ammonia 0, nitrites 0, nitrates 5, ph 8.2. I don't dose anything. I do 5g water changes a week.
Mike Hayes