Weight or volume

[kgriggs]

I am working with balancing a spa and a pool. I am using the Pool Calculator for the pool and another calculator for the spa. I am wondering how most people use the recommendations. It seems most of the information is usually based on weight. I learned on the spa (I had it before the pool) and learned using volume measurements. I have tried a scale to weigh the chemicals but the measurements don't seem to correlate.

 

[chem geek]

Weight measurements are the accurate ones assuming concentrations are known (at least for The Pool Calculator; I can't comment on the other calculator you are using since I don't know what it is). Volume measurements are always approximate and based on a density estimate. You can always measure the weight of a known volume of settled product (tap the cup to settle the contents) and can do your own conversions, but usually The Pool Calculator is pretty good.