Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 2 of 2

Thread: Calculating Volume using Salinity Change

  1. Back To Top    #1

    Join Date
    Mar 2008
    Portland, Oregon

    Calculating Volume using Salinity Change

    Is there a way of calculating the volume of my pool based on change in salinity.
    I recently installed a SWCG (APURE1400). I let it run for a day and the control unit gave me a salinity reading of 0.9 g/L.
    I then added 800 pounds (362874 g) of salt to reach a salinity of 3.2 g/L for an increase of 2.3 g/L.
    Using this as a ratio, I calculate that my pool volume is 157,771 Liters or 41,679 gallons.
    I have always calculated my pool volume at around 35,000 gallons but have never been sure.
    I even went to the trouble of measuring my pool every foot and came up well short of 35,000.
    Would this new figure be accurate?

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    Your basic approach is sound but it is difficult to evaluate how precise it is. At the very best it might be within +-5%, assuming the salt sensor reads perfectly to the closest 0.1 g/L, simply because you only have one decimal place available in the salt level. In reality there will be inaccuracies in the salt sensor it's self that will cause additional errors. I suspect it is more likely to be +-20%, but there is no saying without specifications for the precision of the salt sensor. Keep in mind that your measurement based estimate is only 16% lower than the value you got from the salt sensor calculation.

    To use a chemical measurement approach to measuring pool size we need a chemical test that is accurate to at least two decimal places, and preferably more. You would also need to know how much of the chemical you added to the pool to the same precision. I rather doubt that salt as sold is measured that precisely. The whole process is possible with some creativity, but could get rather tedious if you want it to be better than +-10%.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts