Pool Shock Calculator

Dose the measured FC gap to the treatment target for measured CYA and your actual pool volume. There is no fixed 30 or 60 ppm target for every pool. Each later addition is recalculated from a new reading. Dose only the gap from a fresh FC reading to the CYA-based treatment target. Circulate and retest in about one hour initially; recalculate each addition to restore the target. Check more often if demand is rapid and never repeat a stored dose. Brush daily and filter continuously; clean according to pressure/condition and the filter manual. Recoat D.E. after backwashing as directed by its manufacturer.

Continue until all three criteria pass together: clear water with no visible algae, combined chlorine at or below 0.5 ppm, and overnight FC loss at or below 1 ppm (test after sunset and before sunrise, with no chlorine added or generated between tests). Then return to routine FC targets and the label’s swimming conditions. Clearing can take days or longer; elapsed time alone does not prove completion.

Before swimming, measure free chlorine and pH: pH 7.2–7.8, clear water with the bottom visible, no visible algae, and FC meeting both the measured-CYA minimum and the product label’s re-entry range. CDC minimums are 1 ppm without stabilizer and 2 ppm with stabilizer; stabilized pools may need more. Test FC and pH at least twice daily and more often with heavy use. A calculated dose is not swimming clearance.

Identify the growth before increasing treatment strength. This calculator uses the ordinary algae target, without an automatic multiplier. Clean affected surfaces and accessories using methods safe for the finish. Persistent mustard or black algae needs professional assessment.

Not automatically. Maintain FC for measured CYA and investigate algae, combined chlorine or unexpected demand. An opening without algae can use routine chlorine dosing.