Why Your Pool Keeps Turning Green
A pool that greens once had an event. A pool that greens repeatedly has a condition — something is preventing sanitation from keeping up, and adding more shock each time is treating the symptom.
Likely Causes
Cyanuric acid too high
Excess stabilizer chemically locks up chlorine. You can hold a normal chlorine reading and still have almost no effective sanitation. Only dilution lowers it.
Insufficient pump run time
Cutting run hours to save electricity is a leading cause of recurring algae in Bakersfield summers.
Filter not actually filtering
Worn cartridges, channeled sand or broken DE grids let water bypass without cleaning.
Chronically low chlorine
Intense UV burns off chlorine fast; without adequate stabilizer and consistent dosing, levels bottom out between visits.
Dead spots and poor circulation
Shaded corners, steps and behind ladders green first when flow does not reach them.
Phosphate and organic load
Heavy debris, runoff and landscape material feed algae continuously.
What You Can Safely Check
- Test cyanuric acid — over roughly 100 ppm makes chlorine largely ineffective
- Confirm daily pump run hours are adequate for the pool volume
- Check when the filter was last cleaned and the condition of the media
- Look for algae starting in the same low-flow area each time
When to Call a Professional
Recurring green water almost always needs a diagnosis rather than another shock treatment. We test the full chemistry panel, evaluate turnover and filtration, and tell you which of these is the actual limit.
Safety: Do not swim in a green pool, and never mix pool chemicals together.