This is a little off-topic, but the picture of the rock reminded me to ask the question. I've had 2 different reef aquariums now that had a piece of the texas holey rock in them. After a little while on both of them the water turned a light shade of brown, kinda like a very weak tea. Nothing seemed to be unhappy with this development except for me. Corals and fish didn't care. After trying everything, carbon, extra filters, another skimmer, I noticed a brown spot on one of the pieces of holey rock. I took the rock out, and the water cleared up. When it happened in the other aquarium I didn't notice a brown spot on the rock but when I removed it from the aquarium the water cleared up. My guess is something is leaching from the rock and coloring the water. Can anyone verify that? If so, what is it that's coloring the water?
Thanks,
Brian