I've been using quite a bit of acid as I'm lowering the TA in my pool. I originally had a supply of 31.45% (20 degree Baume) provided by my former pool service, but now I'm buying my own and can only seem to find 14.5% acid -- that's what Lowe's and Home Depot sell.

Does anyone know where I can find the stronger stuff? I live in Tucson AZ.