:grumble:I have a 5g QT and 3 days ago I put a small sixline wrasse in it. It's been up and running for two months with HOB filter, contains filter floss that was seeded in DT. I keep finding nitrites, the lowest readable level, but not 0. I do WC twice a day right now. Params are temp 79, SG 1.024, pH 8.3, 9dkh, calcium 460, nitrates 20ppm, ammon. 0, phos. 0. Any other ideas on dealing with nitrItes? thanks! Ann Marie