No polyp extension after water change

[floral9]

I'm stumped, anyone have a clue what's going on? Did my usual water change a couple days ago and since then my LPS just aren't extending their polyps much. They'll open up a bit, but it's way less than normal. Alk, Ca, and pH levels all look good (11.8, 450, 8.2). Wondering what could cause this after a 20% water change. Only thing that comes to mind is the Alk swing, I usually keep it around 10.4 but it jumped to 11.8 after the change. Ca went from 430 to 450, not a huge deal. pH stayed the same, 8.2. My acans and soft corals seem fine, though.

[zelkor9]

Have you double-checked your salinity levels after the change?

[lumber1x]

I'm with zelkor9, salinity is worth a double check too.

[floral9]

Salinity is 1.0235, it was 1.024 prior to the change. I keep it within a narrow range of 1.023-1.024. It's not always easy to maintain a constant level, my setup is pretty basic - no sump, no auto top-off, no skimmer, and no filter. Despite this, I've never really had issues with my LPS opening up. The tank is 8 months old, and I added my first frogspawn about a month and a half in.

[floral9]

Update on my LPS - my 2-headed hammer is now fully open, the torch is about half, while the 6-head frogspawn is only about half open. My large E. divisa is barely budging, still not opening much. The duncan remains closed, which I'm attributing to the aptasia I removed earlier today.

[zelkor9]

I used to use a swing arm hydrometer, but it was way off - .008 to be exact. That thing wreaked havoc on my corals, they totally tanked. Now I'm a refractometer guy, I calibrate it every couple weeks or so to make sure it's accurate.

[floral9]

Have you double-checked your salinity levels after the change?

I've got one of those basic hydrometers, not the most accurate. Refractometer's on my to-buy list, just haven't gotten around to it yet. Guess I'll be keeping a close eye on the salinity for now.

[felinxo]

If you've got a local store nearby, I'd recommend testing your swing arm against their refractometer - just to get a baseline reading. Also, make sure to rinse thoroughly with rodi after each use, and let it dry upside down. Until you've got a better handle on your salinity and other parameters, I'd suggest sticking to smaller, more frequent water changes.

[floral9]

If you've got a local store nearby, I'd recommend testing your swing arm against their refractometer - just to get a baseline reading. Also, make sure to rinse thoroughly with rodi after each use, and let it dry upside down. Until you've got a better handle on your salinity and other parameters, I'd suggest sticking to smaller, more frequent water changes.

I'm thinking it's time to take a sample in for verification, it's been a bit since I've had the LFS double-check my tests. I do make sure to clean my hydrometer before and after each use, but I'm starting to think I should've grabbed a refractometer when BRS had it on sale. Currently, I do about 4-5 gallons every 2 weeks - do you think I should bump up the frequency?

[finnleyoak]

No relation to the issue at hand, but thanks.