How Long To Wait After Adding pH-Up To Hot Tub

How Long To Wait After Adding pH-Up To Hot Tub

pH Up is a reference name for household or commercial products that are added to a medium to increase the pH level. For hot tub or pool maintenance, pH up refers mostly to sodium carbonate (Na2CO3), popularly known as soda ash, which is used for water treatment. Aside from the name pH up, these products are also referred to as pH increasers or pH raisers.

Hot tubs and pH levels are a pair that never seems to be broken apart. So long as you are using that water-filled box of soothing relaxation, pH levels are bound to rise or drop too. The reasons for this can be anything. pH levels in a hot tub can be the difference between a comfortable and relaxing soak after a stressful day and an itchy and harmful soak in the hot tub. Your hot tub‘s working system is picky about pH levels.

So, you finally notice a pH imbalance in your hot tub water and fix it by adding chemicals. Chemicals do take some time to dissolve and do what they are meant to do, and you do not want to get them on your skin or interfere with the balancing process. But at the same time, you are dying to have a soak as soon as possible, so how long do you have to wait it out?

Some pH-up products have different waiting times depending on the concentration of the product composition. While there is no general wait time for pH-up products, you should stick to the instructions on the product you are using. How long they should stay in the water before hot tub usage is usually indicated on them.

It is not magic! Chemical reactions require time. Gradually, the pH level is going to rise after adding the product, and you do not want to jump in when it is not yet at the ideal level. So a 2-hour wait time should be just enough for pH-up products added to your hot tub to take effect and raise your hot tub pH level to the ideal one

If you used either chlorine or bromine for your pH adjustments, the wait time is going to be longer. They are highly concentrated, so you should wait for about 12 hours at a minimum for the chemicals to fully dissolve and be effective before you proceed to use your hot tub.

Note that the ideal and safe water pH level for a hot tub is within the range of 7.2 and 7.8. If you can achieve the perfect number 7, then better. Below 7, it means increasing acidity levels as well. Considering the volume of your hot tub can come into play too, as regards the quantity of pH up product to use, the amount might not be enough, or maybe too much.

To be certain you have the ideal pH level before soaking, use a test strip to double-check that the pH level is within the ideal range, 20 -30 minutes after adding them. If not yet within the ideal range, add more pH up. Do this until your test strip shows green in the middle, indicating your pH level is in the safe range. Then you can slide in and have that relaxing soak you have been looking forward to all this while.

Low pH in hot tub water screams acidity, which you should say is a danger sign. Very low pH levels or high acidity can cause damage to you and your hot tub components and also alter the chemistry of the water in the hot tub to something not friendly to the skin.

Acidic water is the culprit of discomfort in the hot tub. It causes itching of the skin and a burning sensation in the eyes. Hot tub pipings and liners are not left out. They begin to corrode when in contact with acidic water, and the liners might begin cracking.

What lowers hot tub water pH?

Feeling a bit itchy recently when you use your hot tub? Maybe your hot tub‘s pH level is down again. But you only just added pH up not long ago, and a low pH level so soon is quite surprising, no doubt, because you have used it just a couple of times after the last time you adjusted the pH level. So what exactly is causing the drop in the pH level of the hot tub?

Well, there are quite a lot of factors influencing the drop in the pH level of the water in your hot tub. So using it is not the only reason for a decrease in hot tub pH.

Body fluids like sweat and body ointments like hair cream, body lotions, and cream are made up of acidic substances. Hence, when people soak in the hot tub, they dissolve into the water and accumulate with time and usage, leading to a gradual drop in the pH level of the water in the hot tub.

Other factors include

  • Water source. If the source of water used to fill the hot tub is acidic, well do the maths, the water in the hot tub will also be acidic.
  • Addition of too much pH reducing substance when lowering the pH level of water in the hot tub.
  • Shocking the hot tub can also lower pH. It is always a good idea to shock your hot tub first before adding pH up and not the other way round.

In this article here (you can click to read) we explained in details how these factors contribute to low pH in hot tubs.

Aside from human factors, there are also natural factors causing increasing acidity.

Rainwater entering your hot tub can cause a drop in the pH level. Rainwater has a pH level of about 5, which is acidic and increases the acidity of the hot tub water when it mixes with it. Also, dust, grass, and insects from the atmosphere can alter pH levels when they fall into the hot tub. So always use your hot tub covers when you are not using your hot tub to keep it shut from the atmosphere.

How Long To Wait After Shocking A Hot Tub

How long you have to wait before you can use your hot tub after being shocked depends on the shocking treatment. Shocking is simply the act of oxidizing your hot tub water or adding oxidizing chemicals to the water in your hot tub. This is done to break up organic compounds in the water resulting from dissolved fluids in the body while using it.

Chlorine or any other sanitizing agent can be added to this mixture to help kill any bacteria in the hot tub during the shocking process.

After shocking your hot tub to remove organic contaminants, you should wait at least 2 hours before soaking in it again. While oxidizing agents might be fast, you have to consider the fact that the mixture you are using might also contain sanitizing agents.

Chlorine itself takes a lot of time to fully disinfect water. Depending on how concentrated or potent what is added as a sanitizer is in the mixture, disinfection can take up to 12 hours.

While shocking your hot tub water helps to rid it of organic contaminants, in the process, it also reduces oxidizing chemicals present in the water too. That means lower levels of chlorine and the like, which keep the water bacteria-free.

To reduce how frequently you shock your hot tub, you can try to shower or rinse before soaking, if that is convenient enough for you.

What is pH down?

pH Down is the commercial reference to substances used in making water less basic. As regards hot tubs and pools, it refers majorly to sodium bisulfate (NaHSO4) and muriatic acid (known also as HCL, or hydrochloric acid). These two chemicals are applied to spa water to reduce the pH level when it is high.

How Long To Wait After Adding pH Down To A Hot Tub?

Unbalanced water chemistry, as you know already, causes more harm than good. A high pH will cause scales to form in your hot tub, and that alone can lead to a chain of disaster for both your hot tub and you. Scales in water, aside from causing the skin to itch, deposit and stick to the hot tub surface, making it rather rough for the skin, hence discomforting to use.

A high pH over time can cause a breakdown of your hot tub system entirely. Scales deposit on the hot tub surface, basically anywhere where water flows within the hot tub and accumulates. This can lead to a blockage of the pipes, filters, jets, and other parts through which water is circulated in the hot tub. And restricted water flow will cause pressure to build up against the pump, leading to it being damaged.

So try to stop the degradation of your hot tub by reducing the pH. Wait a minimum of 2 hours after you have added any pH down to your spa water before you use it.

How Long To Wait After Adding Alkalinity To A Hot Tub?

Stable alkalinity will help to stabilize pH levels in your hot tub over time. It helps neutralize acids entering the hot tub water. If alkalinity is low, it can lead to quick changes in the water pH. You might notice a greenish appearance in the water instead of the normal blueish appearance.

You should wait for 24 hours and above before you use your hot tub after adding alkalinity. This is enough time for alkalinity to rise and the neutralization of acids within the water to occur to a safer level.

What should be adjusted first alkalinity or pH?

When it comes to balancing the water chemical levels, between adjusting alkalinity and pH levels, alkalinity should be adjusted first. This will save a whole lot of time and the trials associated with balancing pH levels. Alkalinity makes the water a buffer for the pH level. So if alkalinity is adjusted first to the proper level, it will re-adjust the pH level by neutralizing the acids, keeping it at a safe range.

If pH is adjusted first by adding pH up, it will affect the pool readings if it is excessive. So you might end up with false alkalinity and pH level readings.

How Long before testing a hot tub after adding Chlorine?

After adding chlorine to your hot tub water as a way of sanitizing it, you need to let it rest for a minimum of 2 hours before testing. This is to ensure an accurate reading of the chemical level of the hot tub. Within 2 hours, the added chemical will have dissolved and stabilized.

How fast and how much time it takes chlorine added to water to fully dissipate into it depends on the concentration level. A more concentrated level of chlorine can take up to a day to fully spread into the water. A higher concentration of chlorine will sanitize your hot tub for a long time, but it will take longer to fully mix in when applied.

Temperature also plays a role in how fast chlorine mixes completely into the water. At higher temperatures, chlorine tends to dissipate more quickly.

After dipping your test strip in the sample water, wait for 30 seconds before comparing the emerging color on the strip with the colors on the resulting chart.

There are different types of testing equipment out there, all used to check if the water is capable of being bacteria-free and safe.


There is no perfect or accurate time to wait before using a hot tub after adding chemicals. This is because many factors surround the speed at which these treatments take effect inside water. Hot tubs come in different sizes, and the time required for added chemicals to be effective will vary based on the capacity or quantity of water within the pool.

The best practice is to do some adding and testing to know what concentration of chemicals to add and how long it takes when you add them to your hot tub water.

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