Geos are great, if Ph suppression is a big deal then add a Kalk reactor and run your fuge lighting on a counter cycle to your tank lights to reduce the PH swing. What is your PH now? many corals thrive in lower Ph conditions (7.8-8.0) given you offset the low Ph with High Alk and Calcium levels to promote calcification. Below 7.8 and you are going to have problems. Another way to fight the Low Ph is proper ventilation to the tank, our homes are buttoned up so tight now for energy efficiency that we are often a source of CO2 that lowers the Ph.
-Brett