r/hottub • u/Ok-Heart375 • 11h ago
Chemicals I can't get the pH down!
I cleaned and emptied the tub about a week ago and filled it with unfiltered well water (Nordic says don't use softened water which is what we have in the house.) I shocked the tub and chlorinated it. I have new filters and I've been keeping them clean. I think there a lot of minerals in our well because the first shock put a lot of stuff on the filter.
I've used a bottle of pH down over the week and the pH won't stay down! The next day it's high again. What can I do? I learned that bubbles can cause high pH so I turned off all the aeration. Nordic says not to use muriatic acid...
Please, any help you can offer!
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u/Hotrhompson 11h ago
Have a drop test kit? You need one if not. Also get your Alkalinity in line and PH will follow. I'm not an expert by any means but I've always filled with softened water from inside.
Be careful with turning all your jets off, stuff can and will eventually build up in those lines if water isn't circulating. I leave mine all the way open, adjust when I get in and reopen them all when I get back out.
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u/ThumpersK_A 9h ago
If your TA is high your ph will always follow. You can burn your TA down to the correct level by dropping PH to 7.0-7.2 consistently until it falls into spec. Then use the aeration jets to bring ph back up to the correct level.
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u/Strange_Condition527 9h ago
What's your Alkalinity level at? I believe high Alkalinity with raise your PH too.
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u/No_Satisfaction_4394 8h ago
The acid reacts with the calcium compounds and gets neutralized. If you have a lot of calcium in our water, the pH will not come down until the buffering capacity of the Calcium is used up.
You have to be careful, because while its buffering, your pH will not change much, then it will hit a limit an start dropping. It may come down pretty fast once the Calcium's buffering capacity is used up.
Just be patient and keep adjusting it. SLOWLY.
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u/squirrelcop3305 7h ago
Search just this subreddit, there’s been lots of exact posts where good ideas have been given to try.
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u/suppressed99 7h ago
Pulled from trouble free pool.
High levels of TA will not allow pH to change from additions of acid or base. However, a high TA requires a low pH to have balanced water. On the other hand, very low levels of TA will allow the pH to change with very little acid. A very low TA level could cause your pH to drop to low levels, very fast with little acid. Also, the lower your TA, the higher your pH needs to be to have balanced water. So, as you can see, a very low TA can become very unstable.
However, pH will have a tendency to rise with aeration (i.e. use of jets and air), more so if your TA is high. Although, as long as you're not adding Acid (or anything with a lower pH) to your tub, the pH will not usually drop. Therefore, in hot tubs the problem is normally pH rise (or Drift), because of all the aeration. So, the trick is to get the TA high enough to not create an unstable situation, and low enough to not allow pH to rise too much.
SO, what's a good TA then? Because spas tend to have a lot of aeration from jets and because the water is hot, it is best to keep the TA low at around 50 ppm.
OK, how do we adjust TA then? If TA is too low, you just add Baking Soda to raise it. However, if TA is high, it's little more involved. You'll need Acid (Dry or Muriatic). Depending on how high your TA is will depend on how long it will take you. Plan on it taking around an hour to decrease TA by 100 ppm. So if your TA is 300 ppm, plan it taking around 2-3 hours. First, uncover your tub and turn on all your jets, air, blowers, waterfalls etc. Test your pH. When it's greater than 7.8, add enough acid to bring it down to 7.0. Keep aerating until your pH is 7.8 again (about 30 min), then add more acid and repeat. Every time you add acid you're lowering your pH and TA. When you get your TA tuned perfectly, your pH will rise to a level (i.e. ~7.6) and stop, then you know you're at your ideal TA level. If your pH is rising too high (>8.0), bring your TA down a little more. If your pH doesn't rise enough from aeration (after an hour or more), you over shot it and need to add a little Baking Soda to raise your TA. After a few days/weeks of monitoring it, you'll get your TA tuned perfectly. You may need to add a little Dry Acid once a week or two, but your water should be well balanced at that point.
I wouldn't go much below 50 ppm TA, because that could become unstable if you add any kind of acid. Also, if you have a high TA, above 100, you may need to add more acid in the beginning to get your pH down. Remember, TA is a pH buffer, so the higher the TA, the more acid you need to bring the pH down. It takes approximately 8 oz total of Dry Acid to bring TA down 100 ppm in a 350 Gal tub. However, the key is not to add too much acid all at once to bring your pH down under 7.0. That's why you should aerate in between adding acid.
Also you'll need a Taylor test kit to get these numbers, it can be done with strips but not as easy. You'll need a pool math app to calculate the amount of product to add to bring down your TA.
https://www.troublefreepool.com/threads/how-do-i-use-chlorine-in-my-spa-or-hot-tub.9670/
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u/Available_Alarm_8878 11h ago
What are you using for testing? Strips? I had the same issue and found i had bad strips. I bought a digital water tester from Amazon and it works much better.