To raise your pH for the least cost, use Arm and Hammer Washing Soda from Walmart. Add 1/2 box at a time, via the skimmer, with the pump running. Wait 4 hour between doses, and retest before repeating a dose. Continue adding till your reach a pH level of 7.0 - 7.2. Then, switch to using 20 Mule Team Borax, also from Walmart.

Sorry it took so long to get your membership upgraded. -ben