family swimming in pool

One of the trickiest things about pool maintenance is dealing with the various chemicals you need to keep your pool water healthy and clean. When pool water gets cloudy due to an alkalinity imbalance, one of the ways to reset it is adding acid to your pool. The question then becomes how long after adding muriatic acid can you swim.

The good news is that the time you have to wait after adding muriatic acid is much less than some of the other chemicals that you have to use to maintain your pool water. The minimum amount of time needed to circulate the acid is thirty minutes, but it’s safer to wait 6 hours or longer to avoid some serious problems if it hasn’t dispersed evenly.

What Does Muriatic Acid do to Pool Water

Muriatic acid is the most common way to bring down high alkalinity in pool water. It’s a useful tool, but it can cause burns, eye irritation, and severe problems breathing if you swim through a highly concentrated spot in your swimming pool. You don’t want to take the chance by swimming before the acid is properly dispersed and diluted.

Muriatic acid is often available at the hardware store. But bear in mind that what we want here is not the same as what is used to clean and prepare brick and masonry. Make sure yours is the right concentration for your swimming pool.

Is Muriatic Acid Dangerous

Muriatic acid has a high concentration of hydrochloric acid. It is dangerous. You need to make sure you are careful and protected when you are adding acid to your pool – use safety goggles, acid-resistant gloves, a chemically resistant apron, a plastic bucket and stirrer.

Safety first

Be careful when you are measuring and diluting the acid. Diluting it makes it safer and easier to handle. It’s very important to add the water to the bucket first, and then the acid or you could end up with a nasty chemical reaction.

If you are adding acid to your pool without the pump on, it’s a good idea to brush the bottom of the pool continuously for about a half an hour so that the acid doesn’t settle in one spot. It will destroy the lining of your pool if it has too much contact. You can also run the pump for the first half hour to prevent it from settling and then turn it off to avoid extra aeration.

If the thought of using a dangerous chemical acid in your pool makes you a little uneasy, there are a few alternatives to using muriatic acid.

One of those alternatives is Clorox’s pH down treatment.

How Soon Can Swim After Adding Muriatic Acid

Because it is a dangerous chemical that can cause serious injury if you run into a spot with a high concentration it is good to wait a fair amount of time before you swim. The first half hour is supposed to disperse the muriatic acid, but it’s possible that there will still be strong pockets. Even if it’s diluted it can still do a lot of damage.

It’s generally recommended testing the pool chemistry after about four hours. That’s a good amount of time for it to have properly dispersed. If the levels test comes out good then, go ahead and have a swim!

If the alkalinity is not where you want it, it’s time to add a bit more. This is one of those cases where slow and steady is definitely better, since getting the balance just right is tricky. If you over shoot the mark, you will end up having to balance the pH in the other direction with soda ash or sodium bicarbonate. We want to avoid a back and forth of chemicals, so it’s better to go in steps if you need to.

Why High Alkalinity is a Problem

There are several problems that come along with high alkalinity. Since alkalinity is actually minerals in the water one of the big problems has a very visible clue: the water gets cloudy. The cloudy water is tiny bits of calcium and other minerals floating in the water.

Swimming pool

Just like too much acid, too much calcium in the water can give swimmers itchy eyes and skin. More than the fact that it’s not as nice to swim in, the problem with cloudy water is that these floating minerals build up and can clog the filtration system. They can even permanently damage them if not taken care of.

Another problem is that algae grows better and faster when the alkalinity is high. This is partially because the chlorine doesn’t work as well when there is a lot of alkaline particles in the water. The algae also just like that environment.

And speaking of chlorine not working as well, when the alkalinity in the pool is too high the water is a friendly environment for more than just algae. Bacteria and viruses that the chlorine would normally kill can hang out and make your friends and family sick. 

When you have too much alkalinity in your pool it’s also hard to keep the pH balanced. But isn’t pH the same as alkalinity? Well, not exactly.

Alkalinity vs pH

The difference between alkalinity and pH can be a little confusing since pH is a measure of how acidic or alkaline water is. What we’re talking about here is a measure of total alkalinity, which is all alkaline substances in the water. You measure in parts per million (ppm) rather than as pH levels.

All water has alkalis – things like carbonates, bicarbonates, and hydroxides – and they are important because they keep the pH levels from changing too much. But sometimes we can get too much of a good thing, and we need to balance things back out. A good range for total alkalinity is 80 ppm to 150 ppm.

When you’re adjusting alkalinity, you can also affect the pH levels of your pool. It’s a good idea to adjust carefully, maybe even taking it in stages, so that you don’t unbalance the pH levels when you are bringing down the alkalinity. Using muriatic acid is a good way to do this if you are careful.

Because you don’t want to throw off your pH balance, you may want to add your muriatic acid with the pump off so that the extra oxygenation doesn’t send you past your desired pH levels.

Can I Add Muriatic Acid and Chlorine at the Same Time

NO! You never and I repeat never want to add muriatic acid and chlorine at the same time! These two chemicals do not mix well and can create a dangerous combination.

However, if you do have to add chlorine and muriatic acid at the same time, I would wait at least 1 hour (if not longer) between the two. This will give your pool pump enough time to circulate the pool water, thereby eliminating the threat of the two pool chemicals mixing together.

You’ll also want to make sure that your pool pump is running for at least 6 hours after applying the chemicals. I personally run my pump for a minimum of 24 hours after applying any pool chemicals to the pool water.

What is pH Up

pH Up is a term used by some major brands for a product that helps increase a swimming pool or spa’s pH levels. The brand that I like to use and recommend is Clorox Pool and Spa pH Up.

When the pool’s water pH levels drop below 7.2, it can make keeping your pool looking beautiful a real challenge, not to mention, can cause your eyes to become irritated and red as well as corrode your expensive swimming pool equipment.

Clorox’s pH Up solution is an easy and effective way for managing your pool’s pH levels!

How Long do I Have to Wait to Swim After Adding pH Up

According to, it’s safe to go swimming roughly 20 minutes after adding swim-safe chemicals such as pH Up. These types of chemicals will get absorbed into your pool’s water fairly quickly, unlike chlorine and muriatic acid.

With that being said, my pool care guy prefer that I wait at least one hour before allowing anyone to go into my pool after adding pH Up.


When it comes to the chemistry of your pool, balance is best. Now you know a little more about bringing your alkalinity back into balance and how long after adding muriatic acid you can swim. 

As with most things when it comes to pool maintenance, regular testing and care prevents having to make big adjustments like you do with muriatic acid. But if you do need to take care of the problem, just wait a little while before you jump in again.

Similar Posts