I have a Grecian IG pool 18.5 wide x 37 long , the low end is 36" deep and then slopes down pretty quickly to I believe 8' , whats the most accurate way to get close to the volume without ever being in the pool Physically to measure at the slopes of the deep end and the slope from the low end entering the deep end..and also keeping in mind the angles that are deducted on each corner for the Grecian layout ? Using the average of 3,4,5' as a guess has a pretty substantial difference per foot of water.This is probably one of the stupidest questions out there so far, but I'm trying to get everything as close as I can to make sure I'm draining enough water and have the right #'s plugged into the pool calculator to adjust/balance everything else once I get my CYA levels down...Or am I being to critical for no reason ?