I am having trouble maintaining a FC level. Ph and TA are ok but Cya was at 100. I drained 50% of my 26K pool refilled. Added 3.5lbs of Leslies power powder plus. 5 hours later tested no FC added 2.5lbs more and retested the next morning again no FC. Took a sample to Leslies Ph and TA ok but Cya...