How To Lower pH in Your Hot Tub? (3 Methods)

Having a high pH in your hot tub isn’t something you want. But, luckily you can easily lower the pH levels in a hot tub.

To lower pH levels, you can use sodium bisulfate, muriatic acid, or vinegar. If you lower pH levels, your alkalinity levels will be automatically adjusted too. 

But this is just a quick snapshot. There is more to know about hot tub pH, the right pH level to soak in, and what to do if the pH level is too high. So let’s get on with it.

Can You Use a Hot Tub With High pH?

There are a few instances when you shouldn’t soak in your hot tub water. One of such instances is if the pH level of the water is high.

You shouldn’t use a hot tub if the pH level is high or above 7.6 on the pH scale. This is because the water in the hot tub at that time has a very high alkaline reading and soaking in water like that can cause different problems to you. 

Not to mention the fact that running your hot tub with very alkaline water can also damage the hot tub by causing scale build-up and foam in the hot tub.

Why Is the pH Level of My Hot Tub Always High?

The pH level of your hot tub is always high because the total alkalinity is off. The total alkalinity of the hot tub acts as a watchdog to keep the hot tub pH in the correct range. If the total alkalinity is off or too high, then you will likely have a consistent high pH level in the water.

The pH level in your hot tub could also be high because you added too much pH increaser or too much of a base or alkaline substance like baking soda to the water. If you accidentally spilled baking soda into your hot tub water, it can cause the pH level to be way above the recommended range.

The high pH level could also be a result of your source of water. Hot tub owners that fill their hot tubs with well water have often complained about having a very alkaline reading in the hot tub when they test the water.

Your hot tub water could also have a very high pH level if there isn’t enough sanitizer in the water. The sanitizers that you add to your hot tub water either chlorine or bromine have an acidic content. While the acidic content of each sanitizer varies, having less of the said sanitizer in your water can cause you to have a high alkaline reading in the hot tub.

On the other hand, having too many chemicals or sanitizers in the water can also cause a high alkaline reading. Having too many chemicals in your water will increase the level of TDS (Total dissolved solids) in the water and this can also increase the pH levels of the water.

Other causes of high pH levels in a hot tub include contaminants that fall into the water, hot tub oils, body care products, food residue, and the likes. Any of these can cause the pH level of your hot tub to get very high but if you notice that the pH level of the hot tub stays high consistently, then that is because the total alkalinity has gone wonky.

How To Lower pH Levels In a Hot Tub?

If you have high pH, then here are some methods on how to lower it:

Method #1: Use Muriatic Acid

Muriatic acid is a very common chemical used to lower pH levels in a hot tub. The chemical doesn’t cost much, and it’s very effective.  This chemical is also used to clean bricks because it has a low percentage of hydrogen chloride.

Since muriatic acid is an acid then it can cause corrosion and other problems for your hot tub. You should never pour the acid without mixing it with water first. Also, make sure that you don’t accidentally spill the acid on your hot tub shell.

When you lower pH, you also lower alkalinity. The same product will lower both, but pH tends to lower faster. You have to test for alkalinity levels too.

If you have cartridge filters then you have probably used muriatic acid before to clean filters. If you do, then just use the same to lower pH levels.

Here’s how to add Muriatic Acid to lower pH in a hot tub: 

  1. Test your hot tub water. You must be sure that you have a higher pH than 7.6. To test, you can use a test strip, liquid test, or you can send a sample of your hot tub water to a local spa.
  2. It’s a very strong chemical, so you have to be extremely careful while using it. Having chemical-resistant gloves, a chemical mask, and safety goggles are a must. So, wear them before you start the process.
  3. Based on how high your pH is, measure how much muriatic acid you need. You can check the product container for this.
  4. Mix 1 part of muriatic acid with 10 parts of water in a clean bucket. Use a wooden stir to mix them.
  5. Add the mixture to the water, turn on the jets, and wait at least 24 hours before re-testing.

You should add the water first and then the muriatic acid, never add the acid first. If you do, you might cause different chemical reactions. You should also rinse the bucket properly after each use, and don’t use it for another chemical.

After 24 hours, re-test the water and check the pH levels. If they are still high, then add more muriatic acid and re-test after 24 hours. Or, use our next method.

Method #2: Use Sodium Bisulfate

Another way to lower pH levels is to use sodium bisulfate. Using this chemical is safer than muriatic acid, but you still have to be careful. Also, this product is more expensive. Sodium bisulfate usually comes in the form of a granule.

Sodium bisulfate is mostly used to lower alkalinity levels in a hot tub or pool. But, if you lower alkalinity levels then pH levels will be also lowered.

Here’s how to use sodium bisulfate to lower pH levels in a hot tub:

  1. Wear chemical-resistant gloves, a chemical mask, and safety goggles. Then, test the water to check your pH and alkalinity levels. Make sure that the pH levels are higher than 7.6.
  2. Mix the sodium bisulfate granule with water. Usually, you should add 0.7-1.5 oz per 500 gallons of water. But, check the product container to know the exact formula. Mix it using a wooden stir. The granules have to be fully dissolved into the water before you continue.
  3. Pour the mixture into the water, turn the jets on, and wait for 3 to 5 hours before re-testing the water.

Method #3: Use Vinegar

As mentioned before, when you lower pH you also alter alkalinity and vice versa. So, can you lower pH without altering alkalinity? Yes, using vinegar. Vinegar lowers pH without lowering alkalinity.

Vinegar is an acidic compound that will lower the pH in your hot tub water. However, vinegar should be your last choice because sodium bisulfate and muriatic acid are more effective. But, vinegar costs less and you probably have it already.

Here’s how to use vinegar to lower pH levels in a hot tub:

  1. Test the water and make sure the pH levels are higher than 7.6.
  2. Mix 1 part of vinegar with 3 parts of water in a spray bottle.
  3. Shake the bottle, and pour it all into the water.
  4. Wait at least 6 hours, and re-test the water
  5. If the pH has lowered a bit, then you can add the same mixture until you are satisfied the results.
  6. Or, you can pour 4 cups of vinegar directly into the water. This lowers the pH way faster, but it can also damage your hot tub.

What Can High pH in a Hot Tub Cause?

Having a high pH level in your hot tub is not ideal for the performance of the hot tub. A high pH level in the hot tub can damage the hot tub and ruin your spa experience. Let’s take a look at some of the problems a high pH level can cause in your hot tub.

Scale Build-up

Having a high pH level or a pH level higher than 7.6 in your hot tub water can cause a nasty case of scale build-up in the hot tub.

Scale refers to a chalky substance that forms on the surface and body of the hot tub. The scale is primarily formed because of high pH level coupled with consistent high temperature, and low calcium levels in the water.

The hot tub scale is usually noticed on the hot tub shell, circulation pump, and heater. The scale usually has a whitish appearance and it can have a sandy feeling.

The hot tub scale can also affect the jets in the hot tub. If you notice white flaky substances floating in the water or coming out of the jets, then your hot tub has been affected by the hot tub scale.

Hot tub scale can cause dirty spa water, ineffective heating mechanism, and rust of the metal parts of your hot tub.

Low Sanitizer Effectiveness

If the pH level in your hot tub is too high, it can cause low sanitizer effectiveness. This means the sanitizers and chemicals you add to your hot tub to purify the water wouldn’t work as effectively as they should.

This is because hot tub sanitizers like chlorine work best in low pH levels or slightly acidic water. Since the hot tub water has a very alkaline or very high pH reading, the sanitizers wouldn’t be as effective as they should be.

This can quickly escalate to a bigger problem because if you don’t have active sanitizers in your hot tub, then the hot tub is prone to algae bloom, bacteria attack, hot tub scum build-up, clogging of the filters, and biofilm in the plumbing lines. Eventually, you will have green water in the hot tub.

Cloudy Spa Water

High ph levels in your hot tub water can also cause cloudy or unclear spa water. Cloudy water is caused by unbalanced water chemistry.

If you notice fluffy particles in the water or if the water seems unclear because of dry flakes floating on the surface, then you have cloudy spa water. The nasty thing about having cloudy spa water is that it can start to produce offensive odors.

Discoloration and Staining

Having a high pH level in the hot tub water can also cause discoloration and staining on the shell of the hot tub. Stains that are usually caused by high pH levels are usually green or brown.

When the pH level is too high, the sanitizer wouldn’t work effectively and this can cause green water because there are too many contaminants in the water.

The green water can cause a greenish tint to appear on the shell of the hot tub. You can also notice a brownish tint forming along the waterline. This is a result of too much alkalinity in the water.

Related Read: 6 Things That Could Be Affecting Your pH Levels

Final Words

Overall, having a high pH level in your hot tub water is totally avoidable if you keep tabs on your water chemistry and pH levels by testing them regularly.

If you ever notice that the pH level is off the recommended range, then you should fix it immediately by adding either a pH increaser or a pH decreaser.

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