what are the effects of high salinity on sps?
 

Was hoping for some input or experience on this topic. Cheers.

How high are we talking? Iv had mine up to .031 by accident for a few weeks without any issue. Sps don't mind the high salinity, from my experiences its everything else in the tank that has a hard time with it.

I agree, SPS will be the last to notice the salinity. I recently just had mine drop low (1.017) because my refractometer was out of calibration ... and it was the fish that showed the first signs that something wasn't right ... I never would have noticed because my SPS were showing no signs of stress at all.

Really? I've had exactly the opposite experience. I went out of town for a week when my tank was about 5 months old. I didn't have the ATO system set up yet so I had the R/O float switch plumbed right in to the sump. When I left I set the skimmer cup to empty right to a sewer drain. Something in the tank made the skimmer go nuts while I was gone, and when I got home my specific gravity was 1.018. I think 4 corals out of 15 survived, fish were unfazed.

Too high will kill your fish first. I had mine at 31 one's and killed off one of my fish. SPS showed no problems at all.

Lower salinity is harder on corals than higher salinity.
Try to keep the salinity around 35 to 38 ppt.
Much variance beyond that and the coral will spend a lot of it's energy maintaining it's internal ionic balance.
If the coral spends too much energy maintaining that balance, it will die.

Thanks guys. Some of my corals were not looking as good and realized my salinity was 30

I think this is probably due to how fast your change took place. Your salinity dropped to 1.017 very quickly due to the skimmer malfunction, mine has dropped over the course of a year as my refractometer slowly went out of calibration over a long period of time.

I am now trying to bring it up equally slowly to prevent any issues with the tank. I am topping up with saltwater every other day to slowly increase the salinity without shocking anything.

Lojack, how did your refractometer drifting out of calibration cause your salinity to drop?
When you did water changes, did you add less salt to each batch?

I don't weigh or measure my salt. I have two 80 Gallon Drums, one for fresh RO, and one for Saltwater.

My RO unit fills the freshwater drum and runs off of a float, and it's connected to the drum I use for saltwater, I open the valve and fill the other. I just add salt to the drum, and test the salinity to get it where I want it. Weighing and mixing a set amount of salt with a set amount of water is inconsistent because the batches of salt are rarely on spec and exactly the same.

I was calibrating my refractometer with Distilled water as per the instructions that came with it, then I stumbled across a really good article that was talking about how distilled water and RO water for calibration can cause refractometers to drift. So I bought some Calibration solution that is exactly set to 1.026 concentration and found that my Refractometer was indeed off, by .008 which is fairly substantial in the grand scheme of things.

I intend to add a conductivity probe to my Apex to prevent this problem in the future ... however right now I'm still checking salinity the old fashioned way.