My friend has a kidney-shaped pool with variable depth and he's not a good records keeper, so he doesn't know what's his pool volume. I'm trying to help with water testing and balancing, but obviously without knowing the volume that wouldn't be easy. I can trace the circumference on graph paper with some degree of accuracy, but then the depth variance is hard to measure.
I thought about adding a known amount of chemical and then compare the “before” and “after” test results. Then the pool calculator or another simple calculating method can give the estimated volume. The question is which chemical. Chlorine won't stay unchanged after 8 hours of circulation, and pH and alkalinity won't be accurate because they affect each other. What's left is Ca Hardness. Just add some Ca in order to raise the CH by an estimated 10 ppm and then check the actual change. This should indicate the true volume.
Can anyone comment on this method, and is there a better way?