What is TDS?

TDS is Total Dissolved Solids.

Do We Care about TDS Levels in Pool Water?

TDS is not very important for pool care. It used to be a way to tell when water was "old", but that was before we were able to more accurately measure the components that make it up. Now it's just a relic of a bygone era.[1]

We care about measuring and managing the individual chemicals but the Total Dissolved Solids is meaningless.[2]

What Chemicals Make Up TDS?

TDS in pool water includes Salt, Calcium Hardness, Free Chlorine, TA, and CYA and any other soluble substances that have been dissolved in the water.