Columbus Reef Geek said:Is it red or brown? Looks like either diatoms or red slime, I think it is a diatoms algae. Unless you have a real big tank I wouldn't get a sand star. It will eat a live same bed clean in a tank smaller than a ninety. It will at one point run out of food
Columbus Reef Geek said:Getting rid of diatoms is easy, just keep up on water changes and it will go away. I would add some black turbo snails or cortez red leg hermits. Maybe ten or so of each. The star fish can get a foot wide. If they do starve at that size and die in the sand bed in a tank that size you could have some issues.