And suddenly this...

I wrote about a week ago, that my SG was off. Up to 1.028, according to my LFS. They gave me some of their calibration fluid. I made up some water that day for a water change at night. I wake the next morning to see my corals look happier. I test the water and it reads 1.020...wth?? I recalibrate my refractometer with different fluid to 35 ppt and for the past few weeks I've been bringing my SG back up. Yesterday my SG was 1.023 and every coral looked really happy. Thinking I should really reach 1.026, I added just a little more saltwater to my sump last night. This morning my SG read, 1.023, almost 1.024, but now 2 of my acros don't look happy; neither extended their polyps today and the green one kinda browned out today. My yellow Aussie good torch wasn't happy either.

So, do I drop my SG back to 1.023 or keep going till I reach 1.026?

Tank: 75 mixed reef with 30 gal sump.
TWV: close to 90 gals.
CAL: 440
KH: 9
MG: 1290, I'm working on that
SG: 1.024
Reef crystals salt mix

Oh, I should add, all my fish seem to be doing really well. They are all very hungry and eat well. My false percula clowns laid eggs last Friday and you can see the fry growing. The female has really begun to pig out today, again. I assume she's making more eggs; her belly is getting round again. No snails have died due to this swing in SG. I have 3 snails and literary dozens if not hundreds of baby turbo snails everywhere. All are active at night.

Thank you.

 

I would be surprised if the salinity is the cause of the corals unhappiness. That's not much of a change and was a slow change at that (I think). If you aren't sure, just keep I the same for a while and see how they look. How sure are you of the accuracy of the refactometer? That's where I'd suggest you start.

 

I second what Billme said and might add to test other water parameters just to be sure (like if there was stray nitrates possibly) just to rule that out. Sounds rather strange though.

 

I usually keep two refractometres around just to be sure.

 

Try to raise your salinity by doing water changes with a slight higher sg rather than add saltier water to your sump. Also, I check the calibration of my refractometer every time I use it. It's a very important test and calibrating takes what, 15 seconds? Those tiny turbo's are collonista snails.