I need some help balancing a tank. The Alk is 12.8 dkh (4.57 meq/L), ph 7.8, Cal 450, Mg 1400. I would like to raise the pH to 8.2 and lower Alk to 9-10. The only thing in the tank is about 30 lbs of LR. The tank is not lighted and all the water is about 3 weeks old.