Hello. I have just refilled the 24x 48" pool. I keep adding acid to lower the TA which is 320 from the faucet. The Ph is7.2. Yesterday, I had the TA down to 180 by slowly pouring 2 gallons of acid around the pool. Than we had hard rain and the TA is back to 320 ppm. What's the best way to lower this. How many gallons of acid does it take? It's about 13,600 gallons. Thank you!