pH
A way to measure the acidity or basis of water. Ideal range 7.2 - 7.6. Actual measure determined by regular use of a pool water test kit for that purpose.

ppm
Parts Per Million, a measurement for chemical concentration. Many of the common pool water tests, as well as acceptable ranges, are stated as ppm.

Pressure Gauge
A gauge with a dial indicating the pressure in a closed container such as a sand filter.

Pump
A mechanical device which causes water to flow under pressure for the purpose of filtration or circulation.

Reagent
Tablets, powder or liquid material used in pool water test kits.

Residual Chlorine
The amount of free available chlorine remaining in the water after the chlorine demand has been satisfied.

Return Fitting
A return fitting allows the clean filtered water back into the swimming pool after it has gone through the entire swimming pool filtration process.

Rubber Expansion Plugs
An expansion plug provides a good seal preventing damage to plumbing lines from freezing during winter months.