Quote Originally Posted by polyvue View Post
Have gone to great pains to estimate pool volume, including Free Chlorine and Total Alkalinity titrations (I have pages of notes on the latter if anyone is tired of Seinfeld re-runs), geometric summations, various formulae (including one you authored for estimating spa volume, posted on I forget which forum).... of course, all this effort just made me less sure about the correct volume!
If you have not used this method you might want to give it a try. It works.
http://www.poolhelp.com/ChemicallyDe...oolVolumes.pdf

Here is the link for the "“Simplified Formula Numbers” chart
http://www.poolhelp.com/SimplifiedFormulaNumbers.pdf

FWIW, this is the chart I use to calculate dosage amounts for chemicals by using the formmla:
(Volume of pool / "forumula number" for desired chem from chart) x ___ ppm desired change = ___ pound or quarts of desired chem needed

SO for a 14k pool where you want to increase CYA by 20 ppm it is
(14000/120000)x20=
.1167x20=2.33 lbs. CYA
2.33lbs x 16 oz/lb =37.28 (which rounds to 37.3)