1.025 isn't high at all.... I keep mine at 1.026, as do many others.
Your readings certainly aren't bad
, just on the lower end. You can easily
maintain soft corals (mushrooms, leathers, zoas, palys, etc) and many LPS
with those numbers. First, I would bring up your salinity..... that will give you a little bit higher concentration of minerals just through your pwc
's and should naturally rase your pH a bit.
If you want to get into SPS
, then, yes, you will want to bring them up with either Kalkwasser or 2-part. If you decide to go with 2-part, this is what I use.....MUCH cheaper than store-bought:
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
You'd want to use recipe #1 since your pH is lower, and I wouldn't worry about making the magnesium third part..... You will easily maintain that with your pwc
Are you using RODI