I have been fighting this for a few months. The stuff in the sand seems to clump and is very hard to vacuum because it is as heavy as the sand. I have used Red slime remover, with not much help. My nutrients are Nitrates 12 Phosphates .06 Salinity 35 Alkalinity 9.6. I am dosing Red Sea four part and have been happy with tank for years. Coral do not seem to be affected much. Tangs do not seem to eat it. My clean up crew do not seem to live very long. My sand sifting starfish looked like something was biting it. Can someone help me please?
