I've had good success maintaining my ph as well as calcium and alkalinity using a combination of seachem products along with a regular dose of kalkwasser........here is the routine I follow on a 55 reef
seachem advantage&builder.....rotating days..top-off with approximately 1 gal RODI & 1 tablespoon additive(drip in refugium)
seachem reef buffer.....approximately every 5 days drip 1/2 gal RODI & 1 teaspoon additive
nightly (after lights out) drip 1/2 gal RODI with 1 teaspoon kalkwasser
this routine has maintained ph@8.3 calcium@ 450-500 alkalinity@ 3.5-4.5 meg/l for better than 3 months consistantly
Hope this method helps ya.........folks use different products with equal success....important thing is to establish a routine that gets your chemistry where you need it then maintain those levels consistantly over time......