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Thread: Conflicting Weight vs. Volume Results from PoolMath calculator

  1. Back To Top    #1

    Join Date
    Nov 2015
    North East Florida

    Question Conflicting Weight vs. Volume Results from PoolMath calculator

    I am having trouble agreeing with the volumes recommended by PoolMath, specifically for Calcium Chloride, Borax, and to a lesser extent CYA. Before PoolMath, I always added extra volume because I found that these chemicals are less dense than water, on which a fluid oz is based (1 oz mass water = 1 fluid oz volume). So am I missing a crucial step here - I am starting to think my numbers may be wrong.

    Consider Clorox Calcium Hardness Increaser, from the manufacturer's MSDS sheet, it has a density of .749 g/ml

    Now convert 1 pound mass of Calcium Chloride to an equivalent in fluid oz volume:

    (1 lb) * (453.592 g/lb) / (.749 g/ml) / (29.5735 ml/fluid oz) = 20.478 fluid oz

    So for Calcium chloride, you can assume 20.478 fluid oz / 16 oz mass or a conversion factor of 1.28............but PoolMath has a conversion of 0.8? This is confusing me.

    Similar, 20 Mule Team borax has a density of 48 lb/ft3 or 0.769 g/ml. Doing the above math I get 19.945 fluid oz. per pound, or a conversion factor of 1.247, PoolMath's conversion is approximately 0.959.

    For Clorox's CYA product with a density of 0.897 g/ml I had a conversion factor of 1.069, whereas PoolMath was 1.044.

    Baking soda by PoolMath was exactly the same as my calculation using an average density of 1.201 from engineering toolbox's range 1.121 - 1.281 g/ml.

    I did not check any other chemicals provided by the sheet.
    Current Pool: 8,500 gal IG Plaster, PoolPilot Digital SWCG, star clear filter 90sqft, 3/4 hp superpump, Polaris 360
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  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Conflicting Weight vs. Volume Results from PoolMath calculator

    Bulk density can vary by product. Calcium chloride density is going to vary depending on the granular size of the product and also on whether it is anhydrous or dihydrate. Powder will be less dense than pellets. This MSDS for Dowflake Xtra says 51-61 pounds per cubic foot which is the same as 0.82 - 0.98 g/cm^3 or g/ml. This MSDS for BioGuard Balance Pak 300 says 749 kg/m^3 which is the same as 0.75 g/ml. PoolMath assumes that calcium chloride anhydrous is 1.2 g/ml while dihydrate is 0.84 g/ml. The anhydrous density was determined from GLB product but it does appear that most of the other anhydrous products based on their MSDS are not more than 1.0.

    20 Mule Team Borax in this MSDS is 0.77 g/ml while PoolMath assumes 1.0 g/ml.

    PoolMath uses 1.2 g/ml for baking soda.

    I suggest you measure the weight of a known volume of product tamped down (i.e. tap the container on a hard surface before you measure the volume). The original densities were determined from actual product, not from MSDS, since MSDS had varied. Let us know what you find out.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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