. . . membership upgraded.

We won't really begin digging through the pool chart data till next week, but I glanced at yours. You'd listed that you had an AG pool, but given that you also listed concrete I assumed a typo and changed it to an IG pool. Also, exact gallons in a concrete oval can be hard to calculate, without multiple depth measurements along a center axis. But a 15 x 27 rectangular pool with a typical 3' to 8' profile wouldn't have as many gallons as you listed.

Since I started collecting the pool chart data, I've found that way more than 50% of pool owners have significant volume errors, usually overstating their actual pool volume.