Getting Rid of Algae in Your Inground Pool

Algae can grow in the water and on the surface of the pool. It can cling to the sides and bottom.

Most algae is harmless, but it’s important to know the type of algae that will sting and how much pool shock you will need to use to kill it.

While blue or green algae are the most common type in swimming pools, there are also yellow or black algae that can grow in your pool.

What does a pool do algae cause?

Follow our maintenance guidelines and you’ll prevent algae from invading your home. We recommend using chlorine generators.

When the pH is high or low, algae usually grows.

A stabilizer is a chemical that helps keep the UV light from eating up the chlorine in your water. If you don't have enough of it, then you can dump all of the chlorine into the water.

In a salt water pool, these can cause low chlorine levels:

  • The salt is low.
  • The salt chlorinator system is not functioning correctly.
  • The stabilizer is low.

One of the easiest ways to keep the pool water moving is by using it. Just make sure that you use it.

Should I drain my pool?

Do not drain your pool. Call a professional company first if you absolutely need to.

If your vinyl liner pool is damaged, it could cause the pool shell to pop. Instead of wasting your money, follow these steps to prevent that issue.

Getting Rid of Algae

Pool people refer to this method as SLAM — Shock, Level, And Maintain. This method works by raising the chlorine level and keeping it up until the algae is dead.

Pool people refer to this method as SLAM — Shock, Level, And Maintain. This method works by raising the chlorine level and keeping it up until the algae is dead.


Verify your water chemistry is within the ideal range.

Check your test kit for the ideal range for chlorine, pH, and stabilizer.

If your chlorine is low, test your stabilizer levels too.


Remedy the chlorine problem.

Add chlorine until it’s at the proper level.

Add stabilizer (if needed) to keep the chlorine at the proper level.


Shock/superchlorinate the pool.

Add the shock at dusk or at night so you don’t have to worry about the sun burning off the chlorine.


Add algaecide.

Some pool owners choose to only superchlorinate without adding algaecide. If you opt to use algaecide, make sure you use the best type for your situation.


Brush the entire pool surface with a pool brush.

(Don’t drain to do this!)

Brush everywhere, including steps, corners, and ladders.

As the water clears, you may have to repeat this step.

Sometimes, the solution involves pooling the algae in the pool and then vacuuming it up. In other cases, it's a matter of adding flocculant to make the algae coagulant.


Frequently clean the filters.

Ideally, clean the filter media frequently to keep it running at its optimal pressure. Once the algae has gone, remove it.

If you slack on this step, dead algae will clog up the filters, and you stop making progress.

For a sand filter or a DE (Diatomaceous Earth) filter, you backwash it. For a cartridge filter, you spray it off.


Run the pump on high speed nonstop until the water clears.

Do not turn the pump on or allow the pool to sit for a few hours. Once the algae has settled, remove it and go back to working.

How long will it take to clear the pool?

A fiberglass pool in its worst condition can be algae-free in 24 hours.

For a vinyl liner pool, the process can take 3-4 days.

For a concrete pool, this can take a week or more.

Other causes of green water

If the problem is algae, then add a metal sequestering agent. It will remove it once and then bring it back again. Also, keep an eye on the pool in case it gets SLAM again.


This post was originally published on River Pools And Spas


If you have any other questions about pool and spa products please do let us know - we are here to help!

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