My pool is a 16' x 32' IG with vinyl liner. It has a 3.5' shallow end and an 8' hopper bottom deep end. Every pool calculator I have ever used shows it to be 21,200 gallons based on average depth, but I have always wondered if it was actually that high since there doesn't seem to be an easy way to take the hopper bottom slopes out of the equation. I had been dosing my pool based on the 21,200 gallon number, with .75 gal of 6% bleach giving me 2.1 ppm of FC.
Last week I shocked to what I calculated should be 12 ppm, and the next morning when tested I found out I was actually closer to 15 ppm. I assumed either the bleach was stronger than 6% or I have less water capacity than I thought. Well, over the weekend I was digging for some paperwork and came across the original manual that must have came with the pool when it was installed by previous owners. In it it had a chart showing water capacity for their various sized pools, and my pool is listed at 18,350 gallons, or about 13.5% less than the calculators show.
Not a bunch, but I thought I'd let others know in case they were wondering as well