Acropora tip burn

[NAS]

I see in the back ground that you have a colt coral??? Or some leather by the looks of it. Try (Gasp) running activated carbon for about a week, and crank up your skimmer. A quick scrup will help take any organic toixins out. You will have to keep an eye on your trace's but a regular dose should be fine.

That's my two bits....

PS: The carbon wont be harmfull in the short term regardless of which carbon school of thought you subscribe to.