Pool Acid Washing

Everything You Need To Know

An acid wash is also known as drain and clean. It becomes necessary if your fibreglass pool has turned into a black lagoon. This can happen if you haven't winterised your pool properly. Should the pool have been left stagnant for a long period of time, then algae could have grown in the water. The pool water could also be filled with leaves as well as debris.

A good rule of thumb to help you determine whether your pool needs to be acid washed or not is to check the shallow end of the pool. See if you can see the bottom of the pool clearly. If you can, then it may still be possible for you to restore your pool water with the help of chemicals. But if the floor isn’t visible, then the cost and labour associated with using chemicals are much more expensive than acid washing. It can also take a lot more time.

If there is an extensive algae bloom or if the pool has been neglected, then stains could form in it as well. An acid wash can help you get rid of these stains.

What Is An Acid Wash?

When you acid wash your pool, what you’re doing is stripping a thin layer off from the surface of the pool, exposing the layer underneath it. This is why acid washing isn’t something that you should do regularly. If you do, then you’ll need to get a new floor installed pretty soon.

Maybe your pool doesn’t resemble a swamp. You could just want to bring out a brighter finish to your pool. For mineral stains as well as deposits, as well as chlorine stains and even stains caused by dirt, acid washing can be the solution.

A pool could have been experiencing algae blooms for years. Maybe algae just grow in your pool water easily, and everything you’ve tried has failed. If this is the case, then consider acid washing the floor of your pool.

You’ll also need to change the water in your pool, but after that, you don’t have to worry about algae for the rest of the season. When you acid wash your pool, remember to change out the filter media as well.

Here are three fencing ideas to give you some inspiration for your pool area!

What You Should Know About Acid Washing

Muriatic acid is a substance that is dangerous. You can opt for alternatives that are less hazardous and have less fumes. All those involved in the acid washing process need to be professionals who know what they are doing.

Protective clothing should be worn when acid washing a pool. Breathing masks are also necessary, to prevent people from inhaling the toxic fumes. Before you dispose of the acid or the water waste, ensure that it’s first neutralised. You can do this by adding a pH increaser before pumping the waste out in a safe location.

You could also decide that you want to drain as well as clean your pool by yourself. If you do want to clean your pool, then the first thing you should do is take out the hydrostatic relief plugs as soon as you can. Also, ensure that the waste water is being dumped in a safe location that is far away.

Should your pool sit in an area that is topographically depressed, if your water table is high, or if there has been a lot of rainfall recently, then be extra careful regarding how you manage your pool’s hydrostatic pressure.

Hide the pool equipment with these landscaping ideas!

Note also that you may need to check with your local authorities about how you can get rid of the wastewater.

What Do You Need To Acid Wash Your Pool?

You’ll need:

A long garden hose with a nozzle.

A watering can, that you can use to pour the acid.

A pump as well as a discharge hose, so you can drain the pool and the wastewater.

Around ten to twenty gallons of acid, depending on how severe the stain in the pool is.

Soda ash, which will be used to neutralize the acid. You'll need 2 lbs for every gallon of acid that you use.

An acid safety mask as well as safety goggles.

A screwdriver, that you will need to remove the main drain.

Chisel as well as pliers which You'll need to remove the hydrostatic relief plugs.

Having someone to help you could also be a good idea.

How Can You Acid Wash Your Pool?

This is what you should do, to acid wash your pool:

Drain The Pool And Clean It

You can drain the water in your pool using your filter pump. But you’ll find that there’s some water still left in the deep. A submersible pump can help you to deal with this problem.

After you drain your pool, carefully wash it down to get rid of leaves as well as algae. When the pool is clean, you can start to add acid wash to it. But first, put on your protective clothing.

Check out our comprehensive home pool maintenance guide here!

Pouring The Acid

You’ll need to add equal parts of the acid of your choice, as well as water, to your watering can. Always ensure that acid is added to the water, not vice versa. If you choose to pressure wash your pool before adding acid to it, then you’ll need less acid.

Moisten the pool walls with a hose before you add acid to them. Keep the hose running at all times, without the nozzle. Pour the acid mixture over the walls of your pool, starting from the shallow end. Do this one section at a time.

The acid shouldn’t be allowed to sit for too long. Within sixty to ninety seconds, use an acid brush to scrub the surfaces that are stained. At the same time, move the acid around. Then rinse the area thoroughly.

Make sure you read our how to guide for choosing a child friendly!


Once the acid wash is over there will be a foamy puddle on the bottom of the pool. This will need to be neutralised before you can pump it out. You can do a base demand test to better understand what state the foamy puddle is in.

Use soda ash to neutralise the puddle water. Stir the soda ash in with a pool brush as well as a pool pole. With the help of a pH test kit, you can determine whether the water in the pool has been returned as close to normal as possible.

See the water options for your fibreglass pool here!

Pumping Out The Waste Water

With the help of a submersible pump that comes with a hose, you can pump out the acid water that is remaining. The wastewater, even after being neutralised can still harm animals, fish and plant life – so be careful where you dispose of it.


When you acid wash your pool, you ensure that it looks brighter and is cleaner. However, acid washing can be dangerous so you should have your protective equipment ready if you want to do it yourself. This guide can help you learn how you can acid wash your pool.