Just tested my KH, PH, and Calcium. 50 gallon reef. I recently changed salts from Instant Ocean to Oceanic. KH is usually 8-9, Ph is usually 8.2. After 3 weeks and 2, 20 gallon water changes here are todays numbers..
Calcium=430
KH=4
PH=7.9
I have on hand some Seachem Reef builder, some Kent...