Guide

Why your Florida pool turns green every summer (and how to stop it)

It is not bad luck and it is usually not your fault. Here are the three things that turn a Southwest Florida pool green between June and September, what to do in the first 48 hours, and when it is cheaper to call than to fight it.

941-202-2223

The three causes

• Heat. At 85 to 90 degree water, algae can double every few hours. The chlorine level that held in March is gone by lunchtime in July. Sun burns off unstabilized chlorine even faster.
• Rain. A summer storm can dump two or three inches into the pool in an afternoon. That dilutes chlorine, drops stabilizer, and washes in phosphates from the lawn and cage. Three storms in a week and the water is unprotected.
• Circulation. A dirty filter, a clogged skimmer basket, or a pump timer set for winter hours means chlorine never reaches the corners. Green usually starts in the steps and behind the ladder for exactly that reason.

The first 48 hours

If the water just went cloudy-green and you can still see the bottom, you can often catch it.

• Brush every surface, especially steps, corners, and the waterline.
• Clean the filter and empty every basket so the pump can actually move water.
• Run the pump 24 hours a day until the water clears.
• Shock heavily, then keep chlorine high for several days. Test every morning.
• Do not add algaecide, clarifier, and three other bottles at once. Chlorine and circulation do the work.

When to stop fighting and call

If you cannot see the bottom, if it has been green for more than a week, or if you have already spent $150 on chemicals, the math has changed. Our green-to-clean starts at $350 and usually clears a pool in a few days with commercial-grade treatment and daily visits. Text a photo of the pool to 941-202-2223 and we will price it the same day. We do not drain and acid-wash; if the surface itself is the problem, our sister company handles that.

How to keep it from coming back

• Weekly testing, not monthly. Chemistry in this climate does not hold for four weeks.
• Keep stabilizer in range so the sun does not eat your chlorine by noon.
• Run the pump longer in summer than in winter. Eight hours is the floor, not the ceiling, in August.
• Clean the filter on a schedule, not when the pressure gauge finally forces you to.
• If you leave for the summer, have someone check it weekly. See the snowbird checklist.

Read next

What weekly pool cleaning costs here, or find your town on service areas.