A green pool looks like a catastrophe. It usually isn't. With the right process, most green pools — even ones that look like ponds — come back to clear, swimmable water in four to seven days without draining.
What doesn't work is the thing most owners try first: dumping in shock, waiting a day, and being disappointed. Killing algae is only a third of the job. Here's the whole process.
Step 1: Kill — shock calibrated to your water
Algae dies from sustained high chlorine, and the dose that works depends on your water — particularly your cyanuric acid (stabilizer) level. Pools with high stabilizer need substantially more chlorine to reach an effective kill level; that's why a "double shock" that would clear one pool barely dents another. Test first, then dose to a target, and keep chlorine elevated until the green turns gray-white — the color of dead algae.
Step 2: Remove — brush everything, vacuum repeatedly
Dead algae doesn't disappear; it settles. Every surface needs brushing — walls, steps, corners, behind ladders — because algae embedded on surfaces survives chemical treatment. Then the pool needs repeated vacuuming as the dead material settles out, ideally vacuuming to waste so the debris leaves the pool entirely instead of loading the filter.
Step 3: Filter — long run times, frequent cleaning
Clearing the remaining haze is the filter's job, and it needs to run nearly continuously for several days. Expect to clean cartridges or backwash sand and DE filters repeatedly as they load up with dead algae — a filter cleaning per day isn't unusual early in a recovery. If clarity stalls for days despite good chlorine and a running filter, the filter media itself is usually the bottleneck.
What a green pool recovery costs
Professionally handled, most Cincinnati green pool cleanup projects run roughly $400–$900 across multiple visits, depending on severity, pool size, and filter condition. DIY is cheaper in dollars and much more expensive in time — and partially treated pools frequently relapse, which is how owners end up paying for the chemicals and the pro. Once the water is clear, weekly pool cleaning is what keeps it from ever going green again.
When draining is the honest answer
A small share of pools shouldn't be chemically recovered: extreme stabilizer lockup, years of neglect, or heavy debris layers. In those cases a partial drain-and-refill is faster and cheaper than fighting the water. A trustworthy pro tells you that up front — before selling you a week of chemicals.
Fighting a green pool right now? Request a green pool cleanup quote and a licensed local pool professional will assess it honestly and get it clear.