Pool math, are dry chems measured per scale weight?


Bronze Supporter
Aug 22, 2018
Pool math tells me to add 14lbs of calcium. On a scale, 32 oz in a measuring cup weighs ~1lbs. So do I add 14-32oz cups full, or 7 cups up to the 32oz line? This is a huge variance? I’m sure each dry chemical weighs a different weight.


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Dry chemicals are measured by mass, what you would measure on a scale. Liquids are by volume. English units use ounces for both volume and weight which is confusing. If you switch to metric units it’s more clear - mL for liquids and grams/kilograms for dry materials.