100,000 gal pool

[PoolDoc]

1. Retest CYA by mixing 1/4 cup of pool water with 3/4 cup tap water, and then testing the mix. Multiply your result x4.

2. Assuming a 'box' pool, with all right angles, and calculating 2 boxes, one 24 x 40 x 8 and one 24 x 40 x 5, you end up with ~90,000 gallons. But your pool is probably not a 'box', but is some sort of 'free-form' pool. And probably the transition from 8' to 5' is gradual, and is in the 'deep' section. Also, 5' water depth is VERY unusual, and is something I've never seen. I have seen 4.5' -- and people complained about it constantly.

If you can email your address to me, I'll take a look on Google maps, and see if I can do a better calculation. Another way to calculate volume is to carefully measure TA, add baking soda, wait 4 hours with pump ON, and then retest TA. 40# (you can get it as 8 -12 lb bags or boxes at Walmart or Sams) of soda should increase your TA about 30 ppm *IF* your volume is 90,000 gallons. If you add 40 lbs, and your TA increases MORE, than your volume is smaller.

Test TA accurately, add an exact amount of baking soda, wait, and test accurately again. Give me the EXACT numbers, and I'll recalculate volume.

Meanwhile, you need to be adding at least 5 gallons of PLAIN 8% bleach to your pool EVERY evening.