Pool turned green: can it be saved with chemicals, or does it need draining?

A green pool in Mesa is almost always the same story: the pump stopped, or the chlorine ran out, and it was July. From there, a few days of Mesa heat and sun finish the job.

The useful question is not why it went green. It is whether the water can be brought back with chemicals or whether the plaster underneath is already stained, because those are a $60 answer and a $300 to $800 answer.

The test that decides it (two minutes)

Look for the main drain.

• You can see it, or the vague shape of it. The algae is in the water, not in the plaster. Balance, shock, run the filter continuously and brush daily. This usually clears in two to five days and costs you chemicals. Do that first.
• The water is opaque green and the bottom is invisible. The pool has been this way for a while. Algae has had time to root into the plaster surface, and when the water clears you will find staining that chemicals will not lift.
• The water is black or has a swamp smell, or there are tadpoles. Months, not weeks. Drain and clean, and usually acid wash.

Why Mesa pools go green so fast

Heat. Algae growth accelerates sharply with water temperature, and a Valley pool runs warm from May through September.

Sun. Unstabilised chlorine is destroyed by ultraviolet light within hours in this much sun. A pool that is under-stabilised loses its sanitiser faster than it can work.

Monsoon. Storms from mid-June through September blow dust, pollen, and organic debris into the water in quantity. Organics consume chlorine, so a pool that was holding fine goes under after a big storm night.

Vacancy. Rentals between tenants, houses on the market, snowbird homes shut for the summer. A pump on a timer and nobody watching is how most drained-and-cleaned pools got that way.

What happens if it stays green

Two things get more expensive the longer it sits:

The plaster stains. Algae, particularly black algae, roots into the porous surface. Once that has happened, clearing the water reveals the shadow of the problem rather than solving it, and only acid washing removes it.

The equipment suffers. Circulating heavy debris is hard on a pump and filter, and a pool that has been stagnant for months frequently needs the filter cleaned or the cartridges replaced regardless.

What it costs

Published on the pricing page, and the cost calculator prices your pool now.

One warning about draining it yourself

Do not drain a pool in Mesa and leave it empty. In summer sun, exposed plaster dries and can craze or crack in a matter of hours, and an empty pool is a structural risk rather than a clean slate. A drain, wash and refill is done as one continuous job for that reason. The drained and now cracked page explains what goes wrong.

Get a quote

Send a photo of the pool taken from the deck. The colour, the visibility, and the waterline usually show which of the rows above you are in before anyone drives out, and often the answer is that you do not need a drain. We cover Mesa, Gilbert, Chandler, Tempe, Apache Junction, Queen Creek, and Gold Canyon.