It happens to the best of pool owners. You go on vacation, the pump trips a breaker, the chlorine runs out — and suddenly your pool looks like a pond. A green pool is not ruined. It just needs the right treatment in the right order. Here is how to clean a green pool step by step.
Step 1: Assess How Bad It Is
Green pools fall on a spectrum:
- Light green / teal tint — early algae bloom. Usually recoverable in 1–2 days.
- Dark green, can not see the bottom — moderate bloom. Plan on 3–5 days of treatment.
- Black-green, thick, swamp-like — severe. This may need a professional drain-and-clean or multi-day recovery.
Be honest about where your pool falls. Throwing chemicals at a severe bloom without the right approach wastes money and time.
Step 2: Remove Large Debris
Before you add any chemicals, use a leaf net or skimmer to pull out as much large debris as possible — leaves, sticks, dead insects. Do not try to vacuum yet. Stirring up the bottom just makes it harder for chemicals to work.
Step 3: Check and Clean the Filter
Your filter is about to do heavy lifting. It needs to be clean before you start:
- Cartridge filter — remove and hose down thoroughly. If it is old or degraded, replace it.
- Sand filter — backwash until the sight glass runs clear.
- DE filter — backwash and recharge with fresh DE powder.
A dirty filter during green pool recovery is like trying to mop a floor with a dirty mop. It will not work.
Step 4: Brush Everything
Brush the walls, steps, benches, and floor of the pool aggressively. Algae clings to surfaces, and brushing breaks it loose so the chemicals can kill it and the filter can catch it. Do not skip this step — it makes a massive difference in recovery time.
Step 5: Shock the Pool — Hard
This is not a normal weekly shock. For a green pool, you need to triple or quadruple shock:
- Light green — 2x normal shock dose (2 lbs per 10,000 gallons)
- Dark green — 3x dose
- Black-green — 4x dose or more
Use unstabilized calcium hypochlorite shock (cal-hypo). Add it in the evening when the sun will not burn it off. Run the pump 24/7 during the entire recovery process.
Step 6: Run the Pump and Clean the Filter Again
After shocking, run the pump continuously — 24 hours a day. The water will turn cloudy white or gray-blue as the dead algae gets filtered out. This is good. It means the shock is working.
Check your filter pressure every 8–12 hours. When pressure rises 8–10 PSI above the clean baseline, clean the filter again. You may need to clean it 2–4 times during recovery. This is normal.
Step 7: Vacuum to Waste and Test
Once the water clears to a blue-white haze, vacuum the dead algae off the bottom. If your filter has a "waste" setting, use it — this sends the debris straight out instead of back through the filter.
After vacuuming, test the water:
- Chlorine should be above 5 ppm (it will come down naturally)
- pH should be 7.2–7.6
- Alkalinity should be 80–120 ppm
Once chlorine drops back to 1–3 ppm and the water is clear, you are safe to swim again.
When to Call a Professional
DIY green pool recovery works well for mild to moderate cases. But call a professional if:
- You can not see the bottom of the shallow end
- The pool has been green for more than 2–3 weeks
- Your equipment is old, damaged, or not running properly
- You have already tried shocking and it did not clear up
- You suspect a leak — water loss combined with green water often signals a bigger problem
Green Pool Recovery in Ellis County
At A&M Pool Service & Repair, green pool cleanups are one of our most common calls — especially after vacations, storms, or equipment failures. We have seen it all, from light blooms to pools that look more like retention ponds. We will get your pool back to swimmable condition as fast as possible.
Call us at (214) 399-7347 for same-day assessment. We serve Waxahachie, Ennis, Midlothian, Cedar Hill, DeSoto, and all surrounding communities. You can also request a free quote online — we will call you back within an hour.