Change GAC as you do water changes. If there is a cont. in the tank the carbon should exhaust itself quickly.
Still need to figure out the cause.... What did you do around the house and tank today? Anybody come in to do work? Pest control? Cleaner/maid? Have you cleaned with <u>any</u> chemicals? Have you stuck your hands in the tank at all today or the past 24 hours? Do you have small children? Could they have placed something in there?
This is the time to leave no stone unturned.... what happened?
Edit:
SaltyVixen;932355 wrote: Oh OK, no but I can get some when my husband get home from work . How do I check for stray voltage
I'd be surprised if it were this. Stray voltage effects fish much more than coral. RTN of a chalice and problems with a shroom do not sound like the culprit to me at all.
Edit: FWIW poly pad may help to identify if it's in fact a contaminate and what.... If your running out for carbon, grab a couple of those as well.