Jump to content

Can't Keep my Ph High Enough in Softub


Recommended Posts

Hi There,

I have a Softub 300 gallon (I think, it's not the super big one but the next size down. About 6-ish ppl) and I am having a heck of a time keeping my Ph high enough. Softub recommends that ph stay on the high end of the spectrum, even higher than the "Ok" middle zone if possible. However, It seems like no matter what I do or how much ph I put in, my ph lingers at the low end of "ok" or even just below it. I've followed the directions on the package of "Spa up" products (Both Leisure Time and also Softub brand) and have also added a lot more than directions recommend but it still seems like I have to add ph all the time. 

Even trying "ph lock" doesn't seem to keep it up as high as I supposedly want it.

We do not refill the hot tub too often with hose water and don't "shock" it that often, so I am at a loss of what to do. Any thoughts? Does this happen to anyone else? 

Thanks!

Link to comment
Share on other sites

I will comment, as a retired industrial chemist; I just looked up "Spa Up" online, it's simply 100% baking soda, like less-expensive Arm & Hammer from Walmart.

201601071425_785336304106_600x900__53055

That stated, sodium bicarbonate is essentially a buffer to help maintain pH around pH 7.  To raise your pH you need to add sodium carbonate powder, which is about pH 10.  So get some sodium carbonate 100%.  Looks like Home Depot sells sodium carbonate 100%  https://www.homedepot.com/p/Pool-Time-pH-Up-6-lbs-Balancer-23606PTM/310588667

Note that "Leisure Time Alkalinity Increaser" lists its ingredient as "100% sodium hydrogen carbonate" so is the SAME as sodium bicarbonate and their "Spa Up", very deceptive !!!

 

 

Link to comment
Share on other sites

Sodium carbonate will raise your pH and send your TA through the roof. Unless you are using an acidic sanitizer you will have problems with your pH going too high. A better way to bring up the pH is to use sodium tetraborate decahydrate (20 mule team borax from the Laundry aisle in the green and white box) at twice the dose of sodium carbonate. This will raise pH without a major impact on TA.

However, first I would like to know how you are testing the water. IF you are using strips they are very inaccurate.  What sanitizer are you using and what other chemicals are you adding? Posting a full set of test results not done with strips would also be very useful to help us understand what is going on and why your pH is low (if it is actually low and not just an inaccurate reading from strips.)

Link to comment
Share on other sites

On 8/29/2021 at 11:30 AM, Cusser said:

lists its ingredient as "100% sodium hydrogen carbonate" so is the SAME as sodium bicarbonate and their "Spa Up", very deceptive !!!

There is a reason for this. When a pool/spa store tries to sell the product and a customer says they use baking soda the employees are trained to say, but baking soda is sodium bicarbonate and this product is sodium hydrogen carbonate and is much better and that is why it costs so much more than baking soda! Lots of misinformation and some outright deception in the industry to sell as much product as possible.

Link to comment
Share on other sites

10 hours ago, waterbear said:

Sodium carbonate will raise your pH and send your TA through the roof. Unless you are using an acidic sanitizer you will have problems with your pH going too high. A better way to bring up the pH is to use sodium tetraborate decahydrate (20 mule team borax from the Laundry aisle in the green and white box) at twice the dose of sodium carbonate. This will raise pH without a major impact on TA.

 

I've had my CalSpa since 1988, and have used sodium carbonate to raise its pH, and have never used any borates of any kind.  I've also used sodium borate for similar in my above-ground pool.

On a few occasions I've used powerful 100% sodium hydroxide powder to raise pH in the CalSpa and in my 15' above-ground pool, but this is significantly more dangerous to add (wear gloves, goggles).  https://www.acehardware.com/departments/plumbing/drain-openers/drain-cleaners/4239216

Link to comment
Share on other sites

If you are a retired industrial chemist then you know that the main reason for pH rise in a pool or spa is outgassing of CO2 and that the higher the bicarbonate level in the water the faster CO2 will gas off since we purposely overcarbonate pool and spa water. When an acidic sanitizer source is used (Trichlor, MPS, and to a much lesser extent dichlor and bromine tabs) then a higher carbonation (TA) is desirable for more of a buffer effect to offset the pH drop from the acidic sanitizer. Spas have much higher aeration because of the jets than a pool so the outgassing tends to happen much faster.

You must also know that at the normal pH range of pools and spas carbonate ions do not exist in the water and are converted to bicarbonate and that adding sodium carbonate will cause TA to shoot very high. If the sanitizer source is not acidic (inorganic chlorine sources and sodium bromide oxidized with such chlorine sources) then the pH will rise above desirable levels until the TA ifr broiught down.

Using either borax or lye will not have this impact on TA since you are not adding additional bicarbonate ions as you are when adding either sodium bicarbonate or sodium carbonate, although there will be a slight increase in TA with the pH rise since both will cause a shift from dissolved carbon dioxide in the water toward bicarbonate ion formation.. Of the two borax is MUCH safer to handle and harder to overdose.

Link to comment
Share on other sites

Ok...what I'm hearing from this is that if I use an acidic sanitizer (like dichlor), it's OK to use Sodium Carbonate to increase the pH of my spa w/o raising the alkalinity? Or...what am I missing (not a chemist).

Here is the breakdown of what I'm using in my spa:

Currently I am using the TESPERT Pool and Spa Test Strips Hot Tub Test Strips but I've used several different brands before (including ones I got directly off the Softub Direct and the bottle my Softub guy gave me). How am I supposed to test it if not with these strips?

For sanitizer, I am using the Leisure Time Spa Chlorinating Granules (Sodium Dichloro-s-Triazinetrione Dihydrate) in conjunction with a Spa Frog mineral sanitizer insert which is a new-ish thing to help me not need so much chlorine. It seems to work. 

I pretty much don't put anything else in it except pH Up (Currently it's Leisure Time brand too as the "Softub" brand was out at the time of purchase, but I seem to remember the chemical makeup is the same).

Don't seem to have a problem with alkalinity, though I notice cyanuric acid increases over time if I use too much chlorine.

Though, no matter what I have/haven't done, I've never been able to keep my pH high enough since we got our Spa last year. My Softub rep told me that the pH should be above the "ok" range on the strip to preserve the vinyl lining of the Softub.  

Here is the list of things I bought last time I needed chemicals:

image.png.07e653a114fd6b55f80bab5e0788d6bb.png

Link to comment
Share on other sites

3 hours ago, Lyndsie said:

Ok...what I'm hearing from this is that if I use an acidic sanitizer (like dichlor), it's OK to use Sodium Carbonate to increase the pH of my spa w/o raising the alkalinity?

No, DIchlor is only mildly acidic with a pH of around 6. Read these:

https://www.poolspaforum.com/forum/index.php?/topic/52522-some-truths-about-ph-and-ta/

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

The second one is a bit long but it explains a lot about TA and pH and their relationship.

With that being said I suspect your problem is testing error because you are using strips. I suspect that your pH is higher than you think it is. Strips are notorious for inaccurate pH readings. You want a drop based test kit with phenol red reagent for pH. Even a cheap 2 way test kit from Walmart or Home Depot is better than strips. However, if you go the 2 way liquid reagent route I would get a Taylor K-1000 because their pH reagents will work at higher sanitizer levels  and the color comparative is high quality. However>>>

3 hours ago, Lyndsie said:

How am I supposed to test it if not with these strips?

I would recommend getting a Taylor K-2006 test kit.  It is worth every penny.

https://www.taylortechnologies.com/en/page/231/k-2006-complete-kit-with-fas-dpd

You can order it online from Amazon and many other online retailers. It is worth every penny and will test Free Chlorine, Combined Chlorine, pH with acid and base demand tests, Total Alkalinity, Calcium Hardness, and Cyanuric acid (stabilizer) which is important if you are using dichlor since too much cyanuric acid will overstabilize and the chlorine will not be able to sanitize the water. Dichlor adds 9 ppm cyanuric acid for every 10 ppm free chlorine added so once you have added about 33 ppm of chlorine cumulatively your water is at 30 ppm Cyanuric acid and you really don't want it any higher.

Posting a full set of test results would be helpful in determining what's going on. If there is a dealer or pool store near you that tests water and uses either Taylor or LaMotte water testing that would be best. If they use strips, een with a strip reader machine it's no better than what you have now. If you do only have access to strips then post a full set of results.  Full test results are:  FC, CC (or TC, depending on testing method), pH, TA, CH (or for strips total hardness since they can't test calcium hardness), and CYA. These are the basic parameters that need to be tested, btw.  Once we can look them over we will have a much better idea of what's actually going on. We need actual numbers, not OK, Low, or High.

I know it can seem overwhelming but it's just a learning curve like anything else and it's really not that hard.

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...