Can a green pool be fixed in one visit?

Sometimes, if it is caught early and only lightly tinted. Most green pools take several days of high chlorine, constant filtering and repeated filter cleaning. A pool that has been dark green for weeks may need a drain. We tell you which situation you have after seeing it.

Is it safe to swim in a pool that is slightly green?

No. Green water means the sanitizer is not keeping up, and what you cannot see in the water is the bigger concern. Wait until the water is clear and the chlorine reading is back in range.

Why did my pool go green even though I added chlorine?

Usually one of three things: the pH was high, so the chlorine was not working well; the stabilizer was low, so the sun destroyed the chlorine quickly; or the filter was dirty, so the water was not circulating. Weekly testing catches all three.

Why Pools Go Green in the Las Vegas Heat

A pool goes green when algae grows faster than the sanitizer can kill it. In most climates that takes weeks of neglect. In a Las Vegas summer it can take days, because four things are working against the water at once: heat that drives up chlorine demand, sun that destroys chlorine, wind that delivers dust and debris, and evaporation that keeps pulling the chemistry off balance. Miss a week of testing in July and a clear pool can be cloudy by Thursday and green by the weekend.

The four things working against your water

Heat

Warm water is a better place for algae to grow and a worse place for chlorine to last. Pool water in the valley regularly sits in the high 80s and low 90s through July and August. At those temperatures everything biological speeds up and the chlorine is consumed faster just keeping pace.

Sunlight

Ultraviolet light breaks down free chlorine. Without enough stabilizer (cyanuric acid) in the water, a sunny valley afternoon can strip most of the chlorine out of a pool in a few hours. With the right stabilizer level the chlorine lasts, but it still needs to be replaced every week.

Wind and dust

Spring winds and monsoon-season storms drop a surprising amount of dust, pollen, leaves and seed pods into a backyard pool. All of it is food for algae, and it lands in the pool faster than a skimmer basket can keep up on its own.

Evaporation and refill

Every inch the pool loses to evaporation changes the balance of what is left. Every refill from the hose changes it again. By the end of a hot week the pH, alkalinity and stabilizer readings are rarely where they started, and chlorine works poorly when the pH has drifted high.

Phosphates and algae, in plain language

Algae is a plant. It needs three things: sunlight, warm water and food. The valley supplies the first two for free. The food is mostly phosphates and nitrates, and they ride in on dust, leaves, fertilizer drift from the lawn next door, sunscreen and sweat from swimmers, and sometimes the fill water itself.

Under normal conditions chlorine kills algae before it ever becomes visible. The problem starts when the free chlorine reading hits zero. Algae spores that were being killed on contact suddenly have warm, sunny, well-fed water to themselves, and in July a bloom can go from invisible to green in 24 to 48 hours.

Early warning signs

Slippery steps or walls. Algae is often felt before it is seen.
Dull or cloudy water. The sparkle goes first.
A green tint in the corners and shaded spots. Low-circulation areas bloom first.
Filter pressure climbing faster than usual. The filter is catching what is starting to grow.
Chlorine disappearing between tests. Rising demand is the clearest early signal.

What green-to-clean involves

Bringing a green pool back is a process, not a single pour of a product. The general shape of it looks like this, and the details depend on how green the pool is and how long it has been that way.

Test and net out the debris. We test the water first and remove leaves and large debris so the chemistry has a fighting chance.
Brush everything. Algae clings to walls, steps and the floor. Brushing knocks it into the water where the chlorine can reach it.
Raise the chlorine, in stages. The pool is super-chlorinated and the level is held high until the green turns gray and then cloudy white. Heavily green pools need repeated rounds.
Run the filter constantly and clean it often. Dead algae has to be filtered out. During a recovery the filter can clog in a day and need cleaning more than once.
Clear and rebalance. A clarifier or flocculant may be used to drop the fine haze, then the chemistry is brought back to normal.

A lightly green pool caught early can come back in a few days. A pool that has been dark green for a month, with debris on the floor and no circulation, takes longer and sometimes needs a drain and a fresh start. We will not promise a one-visit miracle. We will look at the pool and tell you honestly what it needs. That is what our green-to-clean service is for, and the consultation is free.

How weekly testing prevents it

The reason a green pool is so expensive in time and chemicals is that it is a recovery. Prevention is cheap by comparison, and it is mostly a matter of rhythm. A weekly visit lines up with how fast chlorine burns off here.

Free chlorine is measured and replaced every week, aiming for a working range of roughly 1 to 3 parts per million, with stabilizer in place so the sun does not take it all back.
pH and alkalinity are corrected, because chlorine kills far better at a pH of 7.4 to 7.6 than it does when the water has drifted high.
The walls get brushed and the baskets get emptied, so the spores never get a foothold and the circulation stays strong.
The filter pressure is checked, and filter cleans are scheduled before the filter stops doing its job.

Chemicals are included on weekly service, which means there is no incentive to skip a dose and no surprise bill for the extra chlorine a hot week demands.

What helps between visits

Run the pump long enough in summer. Most valley pools need a longer daily run in July than in January. We can tell you what yours needs.
Keep the water level up so the skimmer keeps pulling.
After a windstorm, a quick pass with a net takes a minute and keeps the baskets from choking.
If the water starts to look dull between visits, text us. Catching it on day one is a small adjustment. Catching it on day five is a recovery.

For the other half of the summer story, read why Las Vegas pools scale up so fast, and if you are wondering what exactly happens during a visit, here is what a weekly visit covers. Ready for someone else to worry about it? Request a free consultation.