Pool Chemical Calculator

Most polyquat and copper algaecides dose by the 10,000 gallons. Weekly maintenance is about 2 to 4 fl oz per 10,000 gal, and an initial or green-water dose about 10 to 16 fl oz. Add it after chlorine and pH are balanced, with the pump running.

The amount depends on the product. Liquid chlorine and bleach are measured by volume, granules and tablets by weight. Multiply the dose per 1 ppm by how many ppm you need to raise free chlorine.

Household bleach works exactly like liquid chlorine. At 6%, it takes about 2.7 cups (21 fl oz) per 10,000 gallons per 1 ppm; at 8.25%, about 15.5 fl oz. Use plain, unscented bleach only.

In Australia, the UK and Europe, liquid chlorine is usually 12.5% and granular chlorine (cal-hypo) 65% to 70%. Doses per 1 ppm:

Volumes assume the water is filled to about 90% of the wall height.

Muriatic acid (31.45%) is cheaper and adds nothing but chloride; it takes about 26 fl oz to drop a 10,000 gallon pool from 7.8 to 7.4 at alkalinity 100. Dry acid (sodium bisulfate) is safer to store and handle, but adds sulfates; use about 1.3 oz by weight for every fl oz of muriatic. Pour acid slowly in front of a return, always acid into water, and retest after 4 hours. To raise pH, use soda ash; to raise alkalinity without moving pH much, use baking soda.

1. Test the water. Test free chlorine, pH and CYA with a drop kit (FAS-DPD). Strips cannot read the high chlorine a shock needs.
2. Set the shock level. Shock (SLAM) free chlorine is about 40% of your CYA: 16 ppm at CYA 40, 24 ppm at CYA 60.
3. Lower pH to about 7.2. Chlorine works faster at lower pH. Add muriatic acid in front of a return, acid into water, never the reverse.
4. Add chlorine at dusk. Pour liquid chlorine or pre-dissolved cal-hypo around the edge with the pump running, to reach the shock level.
5. Hold the level. Retest every few hours and top up to the shock level. Brush walls and run the filter around the clock.
6. Stop when it passes. Stop when the water is clear, combined chlorine is 0.5 ppm or less, and free chlorine drops less than 1 ppm overnight.

Balance in this order: alkalinity, then pH, then calcium, then chlorine. Free chlorine should be about 7.5% of CYA at minimum and 11.5% as a target. Pool care is weekly work: keep it on a schedule with the home maintenance checklist, and see the deck and concrete calculators for the pool surround.