Once my new pool acid demand had somewhat stabilized after 7 months, my acid demand was down to about 2 gallons a month, my routine being to add it twice a week - about a quart each time.
Last month, I decided to switch my routine to adding smaller amounts of acid every day, to keep a tighter bandwidth (+- 0.1) on my pH deviation from my 7.4 target. Since I have done so, my acid demand has been cut in half. I now put in about 4 oz. a day, which works out to a gallon a month.
Is it just my imagination, or does keeping very tight control of pH swing actually lower acid demand?