hi all members! new to this hobby, start my reef tank from last year, been killing tons of sps and acros, but all high end zoas that i have invested were doing perfect till last week?. realized some of zoa and palythoa close up and changing color to bright pink, when they melt, there are more colonies zoa start doing the same....same dosing and wc as always, don't know what to deal with this, please help guys! thanks in advance!