Help.....SPS coral is dying off. SG is low.

[riceboy]

check your phosphates

[asylumdown]

I had an equipment malfunction while I was out of town shortly after my tank was set up that caused my SG to drop to 1.015 over the course of 5 days. Some (most actually) of my SPS corals were toast, but some survived, and are now thriving. So, 1.021 is probably a whole lot of stress, and some corals might not be able to handle it, but I bet there are plenty of corals out there that could come through salinity that low just fine. It really depends on the species, what it's naturally adapted to, and how healthy it was to start.

Bring the SG back up slowly, and try and sort out if there are any other problems that might be inhibiting them. Also remember that an SPS that has been stressed can take months to fully recover.