I've been using Reef Crystals for years, and was a Kent user before that. Either of these is fine, but I dumped Kent when I got a bad bucket of salt. Louis will recall this - he had me switch to RC about 6 years ago.

Your pH WILL nosedive with a dissolved CO2 increase (carbonic acid) - and this is especially apparent when the new mix isn't aerated well. A good supply of clean air, introduced into the tank will help with the pH swings.
I do question the "10 gallon weekly water changes" and "25 inch depth". How big is this tank? 10 gallons on a 150 might not be enough. Big water changes can preclude dosing, as long as you don't have a lot of SPS.