NASCAR_Dave
Aquarium Advice Apprentice
I have had my tank up and running for about 3 months now, and I bought CaribSea white substrate for my tank (about 125 lbs). I have about 20 peacock cichlids and a couple of syndodontis (one of which has been in my tank about a week). After less than a month my substrate started turning black. Vacuuming has no effect whatsoever, and now I am seeing what almost looks like oil creeping down the bed towards the bottom - you can see it through the front of the tank. The fish seem quite happy and healthy (readings are 0-0-5) and the water looks clear. A friend has told me that this is a normal thing, but I have seen other tanks with white substrates that do not exhibit this characteristic. Is this normal and if not, what do you think is wrong? If it is normal, is there anything that can be done about it other than replacing the rock?