That is a similar reason I was looking at it. The only hydroponics around here is the virtigrow office and they have very little as far as the accesories.
The package of battery acid will make me about 2 1/2 to 3 gallons of PH down and with only using about 10ML for 4 gallons of tap water (this will drop as I up my
nutrient strength) it will last me a long time. Not to mention it is the same cost as a thing of PH down anyway lol
It is also the route I went because it doesnt react with the other choices I made for the system. I wanted to use bleach as my sterilizer due to the low cost and high availability of it. I was going through a lot of H2O2 trying to fight that infection and having owned a pool I am more confident in my ability to manage chlorine levels.