A cloud rises native a drained pool. Inside, a solo swimming pool technician washes down the walls of the pool with his mixture of muriatic acid and water. Together the cloud condenses and also hangs over the pool, the tech, that isn’t wearing a respirator, breathes in the poison.

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In a backyard a few houses down, Eric Nielson watch the cloud and also looks over. That watches as his fellow company technician takes in a big breath in the acid cloud and also passes out. Nielson operation over, dialing the paramedics as he moves.




The tech woke up and also was just fine, however there can have to be a less happy ending. His mistake remained in not watching out for the hanging cloud that acid, which no dispersing. "He was a male who was old enough and also should have known better," claims Nielson, owner of willow Creek Pools in West Hills, Calif.

That’s the way it works v acid washes. "It’s the dangerous if you’re not paying attention," Nielson says.

In general, this procedure is other of a critical resort. Occasionally a pool requirements a wash to attend to cosmetic stains, or remove algae that’s been left to thrive too long.

While this might be a rare job in some parts, appropriate care have to be required to make sure the task is done safely, through the correct precautions in place. Not just that, it also should it is in performed correctly and in a manner that leaves behind a pristine, clean and also clear pool.

Here, PSN take away a look in ~ what goes into acid washing — once to perform it, what methods organization technicians have the right to use to store safe, and what goes into a suitable job.

Why take it a bath?

Acid washes are performed most regularly to eliminate staining. If the refuses come out through normal chemical treatments, then it’s time to think about the opportunity of an acid wash.

The reasons can it is in regional. Southern Florida, for instance, seems to have a preponderance of metal staining in the pools.

“I get a combination of iron and copper,” says note Goodwin, the owner of swimming pool Water Medic in Palm beach Gardens, Fla. “We have a lot of homes ... That are on wells and they’re an extremely shallow wells. Stole is a large problem in those wells.”

Additionally, after the recession, a number of houses in his area got in foreclosure, for this reason he on regular basis gets dubbed out to residences with pools left stagnant for a few years and whose surfaces have actually been stained through sludge and also slime.

In California and also Arizona, the problems generally revolve about algae and calcium. If neglected, for instance, calcium might even develop up and create “stalactites” on the next of the pool, Nielson says. Algae often tends to an outcome from chemistry imbalances.

A much more universal difficulty is copper staining, often from old heaters or another result of imbalanced water.

In preparation

The time of day can influence the job.

Nielson prefers to start early on in the morning once it’s still a little cool out. “A misty, cooler morning or overcast days are the best,” the says. “A drizzly job is ideal. It’s not going to effect the concentration the the acid. don’t have to worry around the sun, and also it keeps the pool moist.”


Halfway home: The difference between an algae-stained surface and also the acid washed plaster deserve to be distinct as checked out in this progession photo from note Goodwin. The procedure is advertise the acid and also water equipment toward the deeper end of the pool, wherein some water is resting.

Credit: image COURTESY swimming pool WATER MEDIC, WEST PALM BEACH, FLA.

The tools needed for an mountain wash is relatively standard and also should be simple for most business technicians come find. Friend will require a hose, sump pump, party of muriatic acid, a bicarbonate such as soda ash, and also a bucket for mixing the muriatic mountain to produce the solution.

Those are the basics. Alternatives include a push washer, spray pump, chemistry or mountain sprayer, a brush and also a watering can such as those provided in a garden.

There are reasons for including or not including the optional equipment, which will certainly be defined further below.

Protection is just one of the most important elements of preparing because that an acid wash. Rubber boots, protective eye wear, and a respirator space necessities.

"I never go without some kind of eyewear on," Goodwin says. "I walk in the start but I only made that mistake once. Simply a tiny splash was every it took."

Nielson put on coveralls similar to those worn through painters. "Some of them breath a little bit, and also you can toss them once you’re done," he says.

Inspecting the pool

Acid washing a pool needs that the ship in concern be drained. when the pool is greatly empty, professionals should check the walls and floor. “The surface ar of the swimming pool determines how solid a mixture you desire to placed on the plaster,” claims Luke Stoten, president of under Under Pool care in Chandler, Ariz.

Look for any kind of flaws ~ above the surface. These can variety from crack to the plaster being too thin to even take an acid wash.

Pros most frequently will uncover bulges or bubbles in the plaster, indicating the it’s separated indigenous the shotcrete. When tapped, these bulges develop a hole sound.

It’s best to prevent acid washing in the existence of any cracks, Nielson says.

If the client insists, have actually them authorize a disclosure commitment to protect against potential litigation. (Although he says having customers authorize one for any kind of acid wash in general.)

If any type of of this surface troubles exist, it’s necessary to fix them or refer the client to someone who can.

But there might be instances when an acid wash merely isn’t suitable — particularly if the surface product is as well thin. Goodwin prefers the plaster to be at the very least 3/8- or 1/2 customs thick. Otherwise a weaker solution need to be used, if anything.

“You have the right to lighten but you can’t eliminate it,” the says. “If you try, you’ll eat so much into it the you’ll produce a weak clues in the surface.”

Attend to light fixtures if the pool has any. Goodwin recommends removing the fixtures and also cleaning the end the niches. The sprays lock out v a water tap or push washer, together it’s mostly loose dirt or algae.

“Algae and also dirt gain behind the niche,” Goodwin says. “If you don’t take out and also clean behind it yes, really good, once you fill it up, all the will leak the end of the irradiate niche and also you’ll have actually a streak under the bottom the the light.”

The process

There may be minor distinctions in how company technicians perform acid washes but, as a whole, a standard and also similar procedure plays the end each time.


After and also before: Pools from exit homes, watched above, frequently reach a state wherein they need acid washing. In some areas, these space the most common candidates because that the process.

Credit: picture COURTESY swimming pool WATER MEDIC, WEST PALM BEACH, FLA.

First, the swimming pool is greatly drained, leaving around a foot or so of water in the deep end.

Next, technicians mix the solution — usually 50 percent acid and 50 percent water. As soon as Goodwin is washing a pebble surface, he might cut the acid content down to 30 percent, because these surfaces might not withstand the substance as well as plaster. Because of the price to change this material, that tries come be an extremely careful with it.

At this stage, technicians additionally have the alternative of including products supposed to whiten the plaster.

With that step finished, ar the sump pump in the continuing to be pool water. During the acid-washing process, that should always be on and pumping the end the water.


A pre-wash and also scrub room recommended before beginning with the acid, in order to remove as much gunk and material turn off the walls as possible, especially from algae-stained pools. Stoten sprays the walls v a hose, climate scrubs through a pool brush.

"If you haven"t washed that down, you’re walking to have to do two acid washes," that says.

Before beginning the wash, that a an excellent idea to plug up any return lines for this reason the acid doesn’t get caught in them and cycle earlier into the pool once it"s refilled.

When it’s time to carry out the actual acid wash, it’s best to begin at the shallow finish so the solid solution will certainly run under to the water in the deep end.

Stairs require special attention, so Goodwin prefers to start there. “Steps or insets, seats... You’ve obtained to it is in careful, you’ve got a horizontal surface ar there,” the says. “You have to wash those off yes, really quick, otherwise you’ve acquired acid eating right into the steps and also the turn.”

Technicians have options when it comes to the application technique for the acid mix. It’s usually a matter of watering have the right to versus sprayer.

Nielson swears by the sprayer. The likes the level of control it affords. “It evenly and you don’t have actually the focused acid flowing down in one area,” that says.

On the various other hand, Goodwin supplies a watering have the right to to hold the solution and pour the on the walls. That believes the sprayers don’t hold up fine in the lengthy run, if the can does.

Stoten uses a watering can, as well. But to for sure consistency, he doesn’t let the mountain rest. Instead, he offers a brush come scrub under the area that he simply doused v the acid.

With the can, Goodwin normally washes one 5-foot ar at a time. The sprayer enables for an ext coverage, for this reason Nielson functions in 8-foot sections.

Regardless of exactly how the solution is applied, it’s vital to extensively spray under the wall when finished, paying unique attention to rinse the cove leading into the floor. Making use of the hose, direct the acid mix in the direction of the key in the deep end. Goodwin recommends leaving the acid on the wall between 30 seconds and also 1 minute. A second or third pass always can be done if the stain is too significant to vanish in a minute.

Throughout the process, it’s important to keep the plaster wet so it doesn’t cracked or dried out. Nielson usually wets under the swimming pool after he acid washes a section and repeats it because that each brand-new section.

As the process goes on, the water will construct up with the acid concentrate. Part let this sit much longer than others. Goodwin lets the deep finish of swimming pool sit v the incoming mountain for around an hour therefore it have the right to dissolve any type of stains.

Nielson moves directly to the next step — adding bicarbonate come dilute the acid and also ensure the it no eat far the plaster. For many techs, adding in the bicarbonate is one eyeball test but Goodwin estimates that the uses in between 2 and 3 pounds. Nielson admits the it relies on the size of the pool and also how much acid is gift used.

Once the shallow finish is done and the walls of the deep finish have to be attended to, it’s time come bail the water out.

“Get all of the water the end so that the color is even everywhere,” Nielson says.

Clean up

Use a sump pump quite than a typical pool pump to send the water out. Goodwin recommends dumping the water in the clean-out in ~ the former of the house.

If enough bicarbonate is used, the acid water have to be diluted enough to get in the sewer mechanism safely, he says. However be certain to follow neighborhood codes as soon as it comes to disposing of the water.

At this stage, the is a an excellent time to change out the main drain, if necessary. Goodwin additionally likes to lug in a wet vac to remove any kind of dirt and also sand in the drain.


First step: it is recommended that acid washing begin on raised horizontal surfaces such together stairs or ledges to allow extra care. The acid has much more time come eat away at plaster if no washed away properly.

Credit: picture COURTESY swimming pool WATER MEDIC, WEST PALM BEACH, FLA.

"It’s choose preparing a surface," the says. "If she prepping a surface ar to paint and you don’t gain all the dirt off, the end result will be poor."

For one extra smooth finish, techs deserve to sand the wall surfaces down after ~ the wash. Nielsen permits the plaster to dry just sufficient so wet material doesn’t come turn off onto the sanding discs and also clog them. He uses a power sander through 60- to 80 grit paper.

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“It smooths every little thing out and seals the pores of the plaster,” that says. “It renders servicing the pool after that like night and also day.”

This deserve to actually aid prevent stains in the future, that adds. When the pores in the plaster acquire sealed, dirt and bacteria have a more difficult time settling into the walls.