They showed up about a month ago and havent gone away. I've been doing 2x 50% wc a week on my 240 and its being filtered with a 55 Gallon sump with 44lbs of biomedia (Mag 18 Pump) and 2x fx5s (one has a turbo twist 12x attached). Just added the sump and uv 3 weeks ago and also took out the huge piece of driftwood that was in my tank.