They may have swimblader issues I had a clown that I aclimated for 3 hrs as I do all new additions and he could not get to the bottom of the tank took him about 4 - 6 days to right him self. just keep an eye on them if any thing you may want your PH at 8.2 but 8.4 is ok but oon the high end for coral growth it would be ok. I would get as much of that red slimmy algae out as I could use a syphon and then put some new water in. This may help, lower salinity a bit to 1.020 and increase temp to 82 add a air stone. This will help them with to get more O2 and if they have any thing it should help them to fight it off. once they are fine again then bring the salinity up to normal over a couple days and drop the temp to 79 - 80.

Bill