AquaChek 7-in-1
Free Chlorine reading of 0 ppm
Critical low
What it means
Free chlorine at 0 ppm means the pool has no active disinfectant. Bacteria and algae can multiply within hours. The water is unsafe to swim in.
What to do
Shock immediately at 1 to 1.5 lb Cal-Hypo per 10,000 gallons. Brush, run pump 8 hours. Re-test in the morning. Investigate why: high organics, low CYA, or expired chlorine.
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