A green pool is almost never a mystery. In Pinellas County it comes down to a handful of causes, and knowing which one you have determines whether recovery takes three days or three weeks.
1. Sanitizer ran out
The most common cause. A week of vacation, a stretch of hot days, or a skipped service and free chlorine drops to zero. Algae only needs a couple of days at that point.
2. Stabilizer lock
Every stabilized chlorine tablet adds cyanuric acid, and it does not leave on its own. When CYA climbs past roughly 100 ppm, your chlorine reads fine on a test strip but barely works. Pools on year-round tablet feeders in Florida hit this constantly. The fix is partial draining and refilling, not more chlorine.
3. Phosphates feeding the algae
Lawn fertilizer overspray, leaves, and rainwater runoff bring phosphates into the pool. Phosphates are algae food. High levels mean algae comes back even when your chlorine looks correct.
4. Filtration and circulation
A dirty filter, a short run time, or a failing pump means chemicals never fully distribute. Dead spots along steps, behind ladders, and in tanning ledges turn first.
What green-to-clean involves
- Full water test including CYA, phosphates, and calcium hardness
- Balance pH first so shock actually works
- Heavy shock treatment plus algaecide as needed
- Brush every surface, then vacuum dead algae out
- Run the pump extended hours and clean the filter repeatedly
- Return visits over roughly a week to hold the chlorine level
We do green-to-clean recoveries throughout Clearwater and Pinellas County, and most customers move onto weekly service afterward so it does not happen twice. Call (727) 222-0467.
Eddie Hardwick owns and runs Clear Waters Pool Care, servicing residential and commercial pools across Pinellas County, Florida. He has spent years balancing Gulf-coast pool water through summer storms, pollen season, and snowbird turnovers.