I have been adding about 1-1/2 gallons of muriatic acid each week to maintain my pool pH. When I check my pH it is normally around 8.0. I add about 60-80 oz. and decrease the pH down to about 7.2 to 7.4 and it increases back to 8 by the next week. I have an intellipH system that adds acid while the pool is circulating but its maximum setting is 2 oz per hour (about 12 oz. per day or 84 oz per week). After a week the pH is back to 8 and I manually add 60-80 oz. more to reduce the pH (total of about 1-1/2 gallons between the manual addition and automatic). Pool is 10 years old with original plaster. I installed the SWCG and pH control about a year ago (been fighting the issue since then). I use the intellipH system to add the large amounts of acid by connecting the acid pump to a 24v supply and running it for 15-20 minutes. I have the intellichlor SWCG set at ~20%. Any help would be appreciated. thanks.