High PH in Hot Tubs

In a hot tub, pH is a very important aspect of water balance. It determines whether hot tubs are too acidic or too scale forming. High pH is a reoccurring issue for many hot tub owners. When a pH is too high in a hot tub, the water becomes scale forming . High pH can cause premature equipment failure and increase your sanitizer consumption.

What causes high pH in my hot tub?

The primary reason for a high pH and the tendency for the pH to stay high is a very high total alkalinity. Total alkalinity is the buffer to keep pH in range. If the total alkalinity is not in range, it cannot buffer the pH to stay in the desired range for hot tubs. Hot tubs in particular generate a lot of bubbles and tend to have higher temperatures. This combination creates a gas called carbon dioxide very quickly. Carbon dioxide builds up and makes the pH go up. This is why hot tub owners, on a regular basis, need to add something to lower their pH and alkalinity. Hot tubbers that have an even harder time lowering their pH is are ones that have well water for the source water – softened or straight from the well, it generally has a high pH and total alkalinity.

Scale from inside pipes

What is scale?

The effect that high pH has on hot tub water is that it is very scale forming. With the combination of high temperature, high pH and even an ideal or low calcium, it can cause white chalky deposits to form on hot tub surfaces. This can be a feeling of sand on the acrylic surface of the hot tub. Hot tub owners may also notice white flakes coming out of their hot tub jets. These flakes may get caught in the filter and plug it. This prevents good water circulation in the hot tub and can create flow error problems. Scale can also form on the insides of plumbing and on the heater’s surfaces. This can cause blockage in the plumbing and prevent proper water circulation in the hot tub or breaker tripping/heater element failure respectively.

Scale on heater element

How to lower pH in a spa

In order to lower pH effectively, hot tub owners must be consistent in adding pH minus to their hot tubs. A product that is used to lower pH is sodium bisulfate. Sodium bisulfate is solid dry crystals which is a dry acid. Acids are used to lower pH into the recommended range for hot tubs which is generally between 7.4-7.6. When adding pH minus, hot tub owners should not add it all at once. The recommendation is to add a designated amount each day until the pH has come down. If pH minus is added too quickly the water will turn too acidic and will need to be brought back up. If pH will not lower after adding the recommended amount of pH minus, hot tub owners can always add a liquid acid which can be more aggressive at bringing down a pH. Chances are the pH is much higher than the actual reading on the test strip. If this is the case, the hot tub owner must continue to add pH minus until the pH is brought down to normal levels.

The real key to problem solving a high pH challenge in your hot tub is to partner with your local hot tub care professional. Take advantage of any free water testing offers they have and use their expertise and advice to make your hot tub care simple as 1-2-3!

Comments

  1. Mark

    Reply

    Hi there

    I have recently bought a spa with a built in salt chlorination system but the instructions on how often to use this were very lacking.
    I added 2kg of spa salt as per the instruction manual and ran the chlorinator for 8 hours then heated the water to 40 degrees.

    Once up to 40 degrees, I tested the water only to find high pH and high TA but I’m not sure if I get a reading for chlorine as there is no visible change on the test strip – so I’m not sure if my chlorine is very high and bleaching the strip or non existent ?
    I have added pH minus several times and both the pH and TA have dropped slightly but the chlorine test remains unchanged.

    Please help

    Many thanks

    • Kathi B

      Reply

      Hi Mark – thanks for the question!
      It sounds like a challenge that most of us that fill the spa with ground water (Well water) source face. It is patience, persistence ands adding the right water balancers at the right time.
      Keep up the slow additions of ph minus – every day until the total alkalinity is in range but don’t add any if the ph falls to 7.2 or less – delay any further applications until the ph rises again.
      Also, are you adding anything to prevent staining and scaling like :https://aqua-tech.ca/store/index.php/hot-tub-chemicals/problem-prevention-stain-and-scale-clarifiers-etc/stain-and-scale-control.html
      In all spas but especially salt water ones, calcium scale happens very easily and this will help prevent premature equipment failure 🙂

  2. Ian J

    Reply

    Hi. I’m new to spa’s having only had one 8 weeks. I have a daily battle with high PH, around 8.1. I add 10 grams /1 level teaspoon on sodium busulphate pre mixed in spa water and the PH falls to around 7.4, perfect, but every day it’s the same story. I was advised to increase TA to around 150 then gradually use the PH- to reduce both to desired level. After a week of adding the PH- the TA level is around 40ppm and PH stabilises around 7.8 but the Clarion Spa chemical used weekly then buffers PH up again and the cycle repeats. The spa was filled with ion exchange water softened water from our domestic softener. Calcium is zero as a result. The water remains crystal clear for around 5 days then not quite so sparkly but not cloudy. Spoke to Clarion Spa who advised the raising of TA then reducing both but it’s a vicious circle. I use a calibrated PH meter and strips to measure TA. I’ve just bought some calcium increaser but not used it yet. I’ve kept marine fish for 25 years with ease so a spa should be a doddle, but it’s not. Any help and advice gratefully appreciated. 🙂

    • Kathi B

      Reply

      It is a cycle you are stick in and, as you have mentioned, each product and each person added to the hot tub effect the water balance. I would advise a change to a weekly care product that is not fighting against your water balance. There are many options but we highly recommend the Trio system – it makes well balanced water EASY! https://aqua-tech.ca/store/index.php/trio.html Another tip is to make sure you close your air controls when getting out of the spa – introducing the extra air can cause ph to drift up.

  3. Reply

    I bought the lazy spa Vegas on Saturday filled it up and done the shock dose of chlorine. Tested it Sunday morning and all levels were fine apart from the high alkalinity and ph level but chlorine was fine. Added the recommended dose of ph minus and it lowers the level of alkalinity and all was fine. Used it heavily Sunday and lost some water. Tested it again that evening and their was no chlorine present and high ph levels. So I done another shock dose of chlorine and filled it back up to water level. Then added the ph minus to try and regulate alkalinity and ph levels. Have been testing it every 24 hours and it still says the same. No chlorine present and high alkalinity. So added a daily dose of chlorine again early this morning and some ph minus. It is making no difference at all to the spa. What am I doing wrong?? Have also cleaned the filter numerous of times and leave filter and heater running constantly as was recommended on lays spa website. I’m stumped as to what it is? If chlorine level was too high surely it would strip the colour out of all the passbook on dipstick. It’s so frustrating as have lovely weather and a few days off work and I can’t use it

    • Kathi B

      Reply

      It sounds like you are working very hard on your chemistry! The best advice we have is to bring a one litre water sample in for us to test. Also to bring with your your stock of product you have at home (or bring the bottled of items themselves). We can then do a full water test and get a comprehensive idea about all the chemistry happening in your hot tub and give you the best advice. At home testing is a good ‘check up’ but it does not have enough data to really give good problem solving help.

  4. Grant debey

    Reply

    Lowering the ph an alkaline in a 200 gal hot tub. The water is city water. Ran through a 20 micron carbon block hose filter and a water softener. I’m up to 3/4 of a cup of ph downer and still have not seen the ph or alkaline budge in the down direction

    • Kathi B

      Reply

      Yes, depending on how high your total alkalinity and ph are to start with, it can be quite the process and it takes time. Patience and persistence are key. We would advise adding 34 grams of SpaGuard Lo n’Slo per day until the ph lowers to 7.2. It will rise again on it’s own (DO NOT RAISE IT) until the total alkalinity is 125-150 on your test kit. IF you can let me know the total alkalinity reading i can approximate the number of doses for you.

      The key is to go slowly – if you lower too much too fast then the water will be in a corrosive state for parts of time and that causes more damage faster than scale formation. Also make sure you are adding SpaGuard Stain and Scale control initially at fresh fill and weekly.

  5. Sharon Rudesal

    Reply

    New to the spa world and am having a difficult time getting the ph level in the right zone. The Alkaline and clorine get in the right area. Have used a whole bottle of PH down and still nothing. Ending up with bubbles and foam. Have drained, cleaned filter and started all over and still PH is very high. At my wits end thinking I have made a huge mistake in this purchase.

    • Kathi B

      Reply

      this is a great question and a very common problem – the key to getting to the bottom of the mystery is really to look at EVERYTHING that goes into the water – every product and every person. Water is a universal solvent – all that means is it makes everything a molecular part of itself so many little or one big thing can be causing the ph challenge. To start with, what products are you adding as part of your regular care routine and have you had your water tested professionally at at hot tub dealer?

  6. Kate Drew

    Reply

    Hi,
    Just bought a new hot tub (Lay Z Spa Helsinki) and I filled it around 4:30pm yesterday and added the shock dose of chlorine. I tested it this morning and all levels were at their highest. I have added some Ph Minus today. So, my questions are:
    How long does the Ph Minus take to work?
    Should I be leaving the cover off whilst the shock dose is in there?
    Should I have added a Ph Minus when shock dosing? Some websites I’ve seen say that if the Ph is too high then the shock becomes useless! HELP! First time spa owner desperate to just get in! 🙂
    Thanks!

    • Kathi B

      Reply

      CONGRATS on your new hot tub! so long as the chlorine level is lower than 8 ppm it is technically safe to use so…enjoy!
      in terms of how long things take, it really depends on the products you are using. Follow package directions and have a dialogue with the folks you bought it from to get their expertise won’t steer you wrong. The shock we recommend has a neutral ph where many shocks can add ph to your water so there are so many factors, it is hard for me to day. However, if things don’t work out with the program you have right now, this is what we use and all our clients love how easy it is and how great the water feels……

      HAPPY SOAKING!

  7. Kirsty w

    Reply

    Can i still use my spa (lazy spa paris) if ph and TA is high? Chlorine is in correct range…i have been adding ph minus but so far nothing happened. I do live in hard water area so judging by others comments that can make it harder to bring down.
    Am new to this so far not been in it in case it causes further problemsm

  8. Annie G

    Reply

    I’m having trouble lowering the ph & ta. I tested our tap water & it ha high ph & ta. I’ve been adding spa down daily, but it’s not going down. Any suggestions?

    AG

  9. Natalie J Marquardt

    Reply

    Hello,
    I recently switched from chlorine to bromine for my spa. I emptied the spa and flushed it out completely prior to refilling with fresh tap water. I am having trouble maintaining the bromine level. The bromine dispenser is dialed in where the directions say it should be for the capacity of my spa, but I keep getting a zero reading. I keep opening it up further to hopefully get more chemical out. I ended up grinding up a tablet to achieve an instant reading and but once it dissipates, the dispenser is not releasing enough to maintain it. So, I opened it up quite a bit further. Still waiting to see what happens on that. My other issue is borderline high PH (about 8) but borderline low TA (barely 80 but looks more like 70) and borderline low CH (about 200). Help! As of now, water looks clear. 🙁

    • Kathi B

      Reply

      these are all great questions and observations….the very best thing would be to bring in a 500 ml water test for analysis when you can

  10. Sarah Kurvinen

    Reply

    Hi, I am really struggling with my water balance. Each day I have started with a really high ph and a nin existent chl8rine reading. I add ph minus and an hour or so later the ph reading is in perfect range, then I add chlorine for a couple of hours in a floater and turn on the heating. By the time its warm enough to enjoy the ph is right up brighter than the top reading and chlorine is really incredibly high too. Next day same routine.. very high ph and chlorine has disappeared again….. so disappointed each evening.
    And a question, how long should I wait to use the tub after adding acid or chlorine?

    • Kathi B

      Reply

      this is a great question and a fairly common problem depending on what style and brand of products you are using. can you tell me more about the brand and product names?

  11. Meghan Mason

    Reply

    New hot tub owner. Dealing with high ph and low Bromine. I understand to add the low and slow each day until the level comes down, but wondering if I continue to just add a small amount bromine each day, or to shock? Bromine levels are consistently low, assume due to high ph.

    • Kathi B

      Reply

      That is a great question – can you tell me more about the bromine you are using? Granular only? Tablets? as well as the brand will be helpful

  12. Di

    Reply

    We flushed the pipes, emptied our hot tub, cleaned thoroughly then filled. All fine for 3 days, 2 of us used twice. Today the water is yellowish/green and smells. The PH is high – I’ve added PH minus, chlorine, scale & stain, non chlorine shock. I’ve been told not to use antifoam or clarifier – is this correct. This happened also recently, only had fresh water in for a few weeks before emptying – had tried the Super Shock sachets 3 times but nothing changed, which is why we emptied, cleaned and re-filled again. Help please.

    • Aqua Tech

      Reply

      Hi Diane!
      The best advice would be to bring in a water sample so we can see what’s going on in the water more in depth! As well as to make sure we get that water in balance as needed.
      If not, that colour could be from a couple of things, it t could be the sanitizer level, which is the most common reason for green/yellow water. Make sure your chlorine/bromine are in the ideal range (3-5ppm) and when you’re shocking have the cover off and the jets on for at least 15 minutes so it has a chance to breathe and gas anything off that it needs to. The next main thing it could be is your filter! Make sure you’re rinsing it every 7-14 days to get larger debris off of it and chemically cleaning every 4-6 weeks to break down any organics, oils and greases that could be in there.

      To get your pH down, please add small amounts over a couple of days and focus on your alkalinity first and foremost. alkalinity is the buffer of pH so whatever you do to the alkalinity, the pH will follow. This may take a couple of days though.

      If the water is cloudy, you can add a clarifier (ours is Polysheen) every 48 hours until clear, and rinsing your filter regularly. If there is foam you can use anti-foam as needed.

  13. Ren

    Reply

    Hi. Ph goes up daily. I add ph- and brings it down to 7.5. Then back up the next day to 8.2 ish. Alkalinity is at 101 broming at 4.1. Just changed the water 4days ago and same problem

    • Kathi B

      Reply

      Thanks for asking such a good question.
      The top 3 reasons why this happens are:

      1. there is a high ph product you are adding that is changing the water balance without you knowing – certain chlorine products are quite prone to this so we prefer to use something like this to ensure this does not happen: Trio Chlorine Granules: https://shop.aqua-tech.ca/products/spaguard-soft-soak-chlorinating-granules-900gm

      2. air controls being left open when you are not in the spa can be causing ph drift – close all the ‘dials’ on the top of the spa so no bubbles are coming out before you exit the hot tub….this allows the water to circulate without extra air being added

      3. if your hot tub has an ozone generator attached many times this gas being introduced into the spa causes ph to rise. Try unplugging the generator from the electrical outlet for a week or so and see if things improve

  14. Reply

    Day 4. I’m a new owner of a hot tub. Alkalinity and PH started sky high. I’ve been adding PH Down by Clorox,93.2 percent of Sodium Bisulfate, each day multiple times. The Alkalinity is now normal on the lower side. Ph is still 8.3 and the Bromein doesn’t even register on test strips. I have added Bromein Granulated powder 4 times now and have changed the type of Bromein tablets, I us. Why is this so hard? The Hot tub is brand new, and we haven’t even entered the water yet. I know it’s a process, but this is getting to be a full time job. Everyone I talk to tells me it shouldn’t be that hard. I have taken a sample of water 4 times now to get tested. They don’t know what else to tell me.

    • Kathi B

      Reply

      Thank you for reaching out! You’re right – i should not be that hard. The most important thing is to establish your bromine level so that you can use and enjoy the hot tub. We would recommend using this Mineraluxe Kit: https://shop.aqua-tech.ca/products/mineraluxe-3-month-bromine-mineraluxe-system-3-month-kit. It is an easy and natural way to maintain your spa AND it is not as dependent on having a lower total alkalinity and ph as other systems. We would advise to add 2 Mineraluxe Cubes, 1 pouch of Oxygen and 4-6 bromine tablets into your skimmer (or fill your floating dispenser and open to max). Wait 3 hours and test your water. If the bromine is 3-5 ppm – then HAPPY HOT TUBBING!. then all you need to do is 1 Cube, 1 Oxygen and keep your bromine 3-5 weekly.

  15. Nivedita

    Reply

    Hi. We just bought a house with hot tub. Drained, cleaned and filled the hot tub. Added around 156gm of Dazzle Ph reducer (over 2 days) and still the test strip shows TA at 240ppm.
    1) Usually, what quantity of Ph reducer does it take to get TA to normal levels when you fill in the hot tub with 240ppm TA?
    2) How much qty of Ph reducer can we put each day? Any limit on qty or intervals at which one can put the Ph reducer?

    Your advice will be really helpful.

    • Aqua Tech

      Reply

      Hi Nivedita!
      It depends on the chemical, every chemical will have a different recommendation based off the volume of your hot tub and there should be instructions on the bottle. I would recommend coming in for a water test though. Getting your water actually tested in a water lab system is the most accurate way of getting a dose for how to bring down your alkalinity and pH! With the pH reducers we sell in our store, it’s very small amounts of pH minus over a certain period of days, usually on average about 4 – 5 days!

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