For a reef tank 1.025 to 1.026 some people run their tanks at 1.022 for a fish only tank. Myself I think that is to low. Do not raise your SG
fast just top off with saltwater instead of RO
water to bring it back up. A LFS
uses a hydrometer to measure their SG
and I asked them what they run their SG
was and they said 1.021 when I got home I checked it against my refractometer it was 1.025 just like mine.
Make sure whatever you are using to check your water has been calibrated.
I don't mess with the PH of my water because it does swing a little with the lighting schedule. Do you have a glass top over your tank? Another reason your PH might vary.