[stephaniesquires]

I am re-doing a tank (see previous posts for the whole story!) and after removing the rock i see white and pink crystalish deposit on the tank walls. What is this stuff? should I remove it for tank health purposes or just to make it look better. It was primarily behind the rocks.

[glampka]

More than likely it's coralline algae. The white stuff is dead so you can remove it. The pink stuff will more than likely die off if the tank is empty & dry. You'll have to scrape it off with a razor blade. Just be careful if the tank is acrylic since you can scratch it.
Within time you'll have more coralline growing in your tank.

[Cela Vie]

That's coralline algae. Slow growing, beneficial AND pretty. With respect to "keeping it" I would say scrape it off to make the tank look better; specially since you have access to it. You really want it growing on your rocks not your glass. I scrap it off my glass where I can reach it, but some areas are just not accessible, but those areas are not that visible (due to the inaccessability? of them). Some people let the back of their tanks get covered with it, which is ok. It's a matter of personal opinion. IMO, it takes away from what's in front of it (i.e., your corals) as corals stand out more in front of dark background. HTH

[Cela Vie]

BTW, did I say slow growing...not in the right environment apparently. The wall of the overflow in my tank is getting covered and that tank has only been running for 1.5 months. I guess I can't scrape that off (at least not with a razor blade). Any ideas glampka (not tryign to take over your thread stephanie).