I have a 55 gallon fish only tank, and I've bought about a little less than 50 pounds worth of base rock from my LFS
to stack up and decorate with. The rocks have seemed to grow light brown gunk on them, and a few weeks ago, red gunk/slime started growing on top of that.
I bought some red slime remover, which got rid of it pretty quickly. After testing, I found that everything was near perfect except my phosphate level was very high, which must be why I had the red slime. So I put some carbon in the filter, and started changing 5 or so gallons of water each week.
Unfortunately, my Yellow Tang must have been picking at the rocks because its lips were stained red. It seemed to be doing fine for a good week and a half, although the redness wasn't going away, but it suddenly took a turn for the worse last night, and this morning it died.
My questions, I guess, would be...
Is the brown gunk on the rocks normal?
Shouldn't they be turning a healthy green color?
Was the red slime stained on the Tang's lips the cause of death?
Do I need a skimmer or some kind of product to get my phosphate down?
PS. this forum is great, I'm learning a lot.