CPO cheat sheet
CPO · Keep the key ideas within reach.
Water Management
Turnover time (hours) = pool volume (gallons) ÷ flow rate (gpm) × 60; a 20,000-gal pool at 50 gpm turns over in 6.7 hours.
Combined chlorine = total chlorine − free chlorine; a combined chlorine reading above 0.2 ppm indicates chloramine buildup requiring breakpoint treatment.
Breakpoint chlorination requires roughly 10× the combined chlorine concentration of free chlorine to oxidize chloramines.
Cyanuric acid above about 50 ppm suppresses chlorine efficacy; keep free chlorine at 7.5% of CYA level to maintain sanitizing power.
Free chlorine residual should be at least 1 ppm in public pools; pH range 7.2–7.8 keeps hypochlorous acid (the active sanitizer) dominant.
Saturation index (SI) = pH + TF + CF + AF − TDS factor; keep SI between −0.3 and +0.3 to avoid scaling or corrosive water.
Total alkalinity 80–120 ppm buffers pH; low TA causes pH bounce, high TA locks pH and causes scaling.
Flow rate (gpm) = pool volume ÷ turnover time (minutes); use this to size pumps and verify filter adequacy against local code.
Backwash a sand filter when the pressure gauge rises 8–10 psi above clean starting pressure or per manufacturer schedule.
Safety
Fecal incident response: formless stool requires raising free chlorine to 2 ppm at pH 7.5 or less and holding 25 minutes (Cryptosporidium: 20 ppm for 12.75 hours).
Formed stool: raise free chlorine to 2 ppm, pH 7.5 or less, hold 25 minutes, then remove stool with a net - do not vacuum.
Lifeguard 10/20 rule: scan the entire assigned zone every 10 seconds and reach any point in the zone within 20 seconds.
CPR compression rate for adults is 100–120 per minute at a depth of at least 2 inches (5 cm); full recoil between compressions.
AED sequence: power on, attach pads, clear the victim, deliver shock if advised, resume CPR immediately for 2 minutes before reanalysis.
Emergency action plan (EAP) must be rehearsed; the first responder activates the whistle signal, clears the pool, and calls 911.
Spinal motion restriction: stabilize head in line with the spine, keep the victim in the water until backboard and straps are ready.
Chemical storage: separate oxidizers from acids; never store chlorine and muriatic acid together - mixing releases toxic chlorine gas.
Water clarity rule: the main drain must be clearly visible from the deck; if not, close the pool until clarity is restored.