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PH 7.7 but TA =20ppm?


westernk

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Hey guys. New water and I'm struggling with this how are these readings even possible (confirmed ph with Taylor kit and the spa boy probe) 

If I add baking soda to increase TA won't it drive the PH even higher? 

(The PH is slowly drifting up but not much by 0.1 over 3 days) 

 

Saltwater tub with salt =2200ppm

FCL =5ppm

Temperature = 98F

Borates =50ppm

CH measured before adding chemicals =130ppm

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43 minutes ago, RDspaguy said:

Ph and alkalinity are 2 of 4 variables that determine water balance, also called saturation index. The other 2 are temperature and calcium hardness. 

https://www.pentairpool.com.au/128/Calculators/Saturation-Index-Calculator

Thank you. I was actually looking at the same site yesterday.  

There appears to be a "bucket trick" to increase alkalinity but not ph. Will attempt soon and post results here. 

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1 hour ago, RDspaguy said:

Ph and alkalinity are 2 of 4 variables that determine water balance, also called saturation index. The other 2 are temperature and calcium hardness. 

https://www.pentairpool.com.au/128/Calculators/Saturation-Index-Calculator

Thank you. I was actually looking at the same site yesterday.  

There appears to be a "bucket trick" to increase alkalinity but not ph. Will attempt soon and post results here. 

Screenshot_20201008-195545_Chrome.jpg

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Bucket trick does not work but this fallacy had persisted since the 60s when it was first proven false! IT DOES NOT WORK!!!!!!!!!  DITTO FOR  WALKING VS. SLUGGING! There have been actual scientific studies done that have disproved this but it just won't die and is even taught in some CPO (Certified Pool Operator) courses for commercial pool and spa mantenace!

It is entirely possible to have a very low TA and high pH. TA is a buffer that keeps pH from crashing downward, not rising. Other factors contribute to pH rise! Maintaining TA withing a proper range (explained below) in addition to a borate rante of 30-50 ppm will help lock your pH around 7.7-7.8 for a longer period of time than without the borate and is the pH level you should strive for for the most stable pH. The lower you move your pH the faster it will rise so don't try and make it too low!

pH rise is caused mainly by outgassing of CO2 (think aeration, which is a constant in hot tubs and spas) so it is something that will always occur and has to be monitored and adjusted. Therefor running a lower TA (50-70)when using certain types of sanitizers can lead to better pH stability. These would be the pH neutral sanitizers: unstabilized chlorine sources--sodium hypochlorite (liquid chlorine or bleach and salt water chlorine generators which produce sodium hypochlorite) , calcium hypochlorite (cal hypo), and lithium hypochlorite. These are alkaline when added to the water and have an acidic reaction when they "sanitize" and are used up so the net pH change is 0 or very close to it.

If you are using an acidic sanitizer/oxidizer  (bromine, dicholr, trichlor, all of which are acidic when introduced into the water and further acidic when they "sanitize" and acidic oxidizers /shocks --Potassium Monopersulfate-MPS or Hydrogen peroxide ) then you need to run your TA higher (80-100 ppm or possibly even higher) to counter the downward trend your pH will take to prevent a pH crash (very acidic water that can damage your tub). be aware that both trichlor and MPS are extremely acidic and if you are using either then you need to closely monitor both TH and pH to prevent problems. Borate is not as effective with these chemicals but is still a useful addition for its algaestatic properties.

NOW TO ANSWER THE OPs QUESTION:

Yes, adding baking soda to raise you TA will raise you pH. Since you have a chlorine based salt system raise your TA to 50-70 ppm give it 24-48 hours to stabilize and then test .You would then add acid to lower the pH to around 7.7 or slightly below. You can test after about a hour of circulation without aeration. Remember, the lower the pH the faster it will rise so try not to go below about 7.5 if possible. Since you have borate in your water you will find that the pH will rise to about 7.7 and stay there for a while. When it climbs above 7.8 lower it again and test your TA if yo have not tested it for more than about 2 weeks. This is how to obtain maximum pH stability in your case. When your TA drops below 50 bring it up again to target. Ditto for when your borate drops below 30 ppm. Also, limit aeration to when you are actually using the tub since the more aeration the faster pH will rise. Finally, if your tub is plaster you need to bring up your calcium hardness to about 300 ppm. if you tub is acrylic or fiberglass a CH of 130 ppm is ok but personally I would bring it up to around 200 ppm. Also, I noticed that you did not list your CYA level, which is important for a chlorine system so without that reading my numbers above are just ballpark numbers.

IF you are interested in the chemistry of bicarbonate alkalinity and pH in layman's terms this link is good reading!

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

 

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On 10/8/2020 at 9:45 PM, westernk said:

Interesting article on ph rise in saltwater systems.  The question I have now is does a low TA really cause corrosion or is it the low PH that is assumed you have just because you have low TA? 

https://www.poolspanews.com/how-to/maintenance/solving-the-saltwater-ph-problem_o

There is SO MUCH MISINFORMATION in this article that I don't know where to start. The information on chlorine efficiency vs pH ONLY applies to pools with NO stabilizer and this is NOT the case with a SWCG since the recommended stabilizers levels fall in the range of 50 t0 100 ppm with most around 80 ppm.

CO2 systems will lower pH and help maintain it. Another way to automate pH control is with a dosing pump adding acid. With either a CO2 system or a dosing pump you would need an electrode for pH and controller to monitor the system. I can tell you that these are NOT low maintenance no inexpensive item. You can also add an ORP controller and electrode to monitor and maintain chlorine levels automatically. Initial investment will usually set you back around $2000 or more for a pool and electrode do need to be calibrated and/or replaced on a regular basis.From what I can see the main purpose of the article was to promote the sale of CO2 injection systems. A much more cost effective way with, IMHO, much less maintenance is running the TA at around 60 ppm and adding borate to 50 ppm and then maintaining pH at the "sweet spot" of 7.7. This is why I do in my own pool/pa and I can tell you, I am lazy when it comes to taking care of my pool and spa I test my water on a regular basis, maintain my chemicals and keep it clean and my pool is open year 'round since I live in Florida. I have maintained commercial pools in the past and know the problems that can be encountered with dosing pumps, controllers, etc. first hand which is why I choose to avoid them at home!

 

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Thank you waterbear for the great information 

The bucket trick raised the TA to 40ppm but the PH also shot up to 7.86 (I have an orp probe) so yes you are right it does not work. 

You ask about stabilizer.  I have no stabilizer in my tub I have never added any cyanuric acid.  Should I be adding CYA? I always thought CYA is a part of dichlor hence it comes with the package and since I'm generating chlorine from a salt cell I wouldn't need to bother with CYA

Will a TA of 30ppm corrode my components? Or is it really the low PH that is responsible for component corrosion? 

My tub is an Arctic Yukon I'm assuming it's fiberglass

Will raise the CH to 200 as you suggest. 

You also mentioned chlorine in efficency at high PH is only if you have no stabilizer since my PH is in the high range is this another reason to add CYA? 

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14 hours ago, westernk said:

Thank you waterbear for the great information 

The bucket trick raised the TA to 40ppm but the PH also shot up to 7.86 (I have an orp probe) so yes you are right it does not work. 

You ask about stabilizer.  I have no stabilizer in my tub I have never added any cyanuric acid.  Should I be adding CYA? I always thought CYA is a part of dichlor hence it comes with the package and since I'm generating chlorine from a salt cell I wouldn't need to bother with CYA

5 ppm with no CYA is extremely high. Is there a recommendation for CYA from the manufacturer of your salt system (or are you running sodium bromide or "Dead Sea Salts" in which case you are running a bromine tub and not a chlorine tub and CYA is not needed).

Will a TA of 30ppm corrode my components? Or is it really the low PH that is responsible for component corrosion? 

Low pH is the cause of corrosion. TA has nothing directly to do with corrosion.  High pH combined with high TA and/or CH is what leads to scaling or can cause cloudy water if calcium carbonate precipitates out. HIgh pH can also contribute to metal staining if there are metal ions in your water.

My tub is an Arctic Yukon I'm assuming it's fiberglass

Fiberglass reinforced acrylic shell. The acrylic is what touches the water.

Will raise the CH to 200 as you suggest. 

You also mentioned chlorine in efficency at high PH is only if you have no stabilizer since my PH is in the high range is this another reason to add CYA? 

In a word, yes. but what does the manufacturer of your SWCG recommend? Also, your pH is NOT high for a system that has 50 ppm borate, 7.7 is ideal. You need to get the TA up to the 60 ppm area though. pH will go up but lower it with acid. IF you go too low it will come back up and stabilize around 7.7 Just keep your TA between 50-70 ppm, borate 30-50 ppm, and pH hovering around 7.7. I personally would not lower it until it hits 8.0 and then try not to drop it below 7.6. If you are nunning sodium chloride and not 'Dead Sea salt" or sodium bromide you might want to consider getting your CYA up to around 30 ppm and running your FC in the 3-5 ppm range. Finally, remember that the more aeration the faster the pH will rise so only turn on your aerators when using them and if you have a low circulation speed use that instead of high speed when just circulating the tub to keep it hot. I assume you keep the tub covered. It's a good idea to uncover it and run it at full speed with aeration for a few minutes before getting in to help remove the volatile oxidation byproducts that form in the enclosed system. UV (if you have it) or shocking with MPS also helps with their removal. If your tub is always uncovered and exposed to sunlight then the oxidation byproducts are not really a problem.

 

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-Its using the arctic spa dead sea salts and its definitely a chlorine tub as per the user manuals :  https://arctichottubparts.com/hot-tub-care/salt-water-care/onzen-sodium-chloride-sea-salt-blend-2kg-pail.html

From the manufacturer:

  • "When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6". 
  • " Salt systems naturally drive pH levels to increase, strive to achieve a balanced pH level"
  • "adding salt to the spas water will increase the pH level. The chlorine that is produced by a salt chlorinator plays a role in the water chemistry of a salt spa. Salt is sodium chloride. When an electric charge is passed through salt water, the sodium chloride is turned into sodium hypochlorite. This is the same kind of chlorine that is sold by the gallon as liquid chlorine. The most important feature of sodium hypochlorite is a high pH. When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6"
  • "It is recommended that calcium be removed from the water in advance, during the fill process with the aid of a pre-filter and when establishing initial correct water chemistry, rather than adding a scale remover after the fact. Calcium readings below 150ppm should be maintained"
  • "545 – 550 mV Spa Boy Optimum Range.
    (Optimum Range is the default factory setting, the
    user may adjust higher if preferred by contacting
    their dealer to have it adjusted. )
    Depending on the water chemistry which will be
    effected by bather load and spa usage, at times
    the ORP value will overshoot or undershoot the
    Optimum Range.
    Note: Using a Drop Test Kit, a 0.5ppm Chlorine
    reading = approximately 550mV"

- My current ORP is ay 850 MV and I keep the FCL high because if you keep it at 545 mv the water gets so cloudy after use and takes forever to get back to normal as they say adding granular chlorine shock is not recommended as it poisons the ORP sensor

- No mention at all of CYA from the manufacturer.  

- What's really confusing me now is the game of achieving TA =50 ppm and then having the PH rise to 7.9 and then lowering the PH and hence lowering the TA and the process starts again with no clear stabilization in my opinion.  Is it possible that saltwater spas with borates (manufacturer makes no reference to borates)  maybe are ok with the low TA ?

-I will let PH go to 8.0and then lower the PH to 7.6 and report back on my success.  Will turn off the aerators

 

Really really appreciate the troubleshooting help!

 

 

 

 

 

 

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8 hours ago, westernk said:

-Its using the arctic spa dead sea salts and its definitely a chlorine tub as per the user manuals :  https://arctichottubparts.com/hot-tub-care/salt-water-care/onzen-sodium-chloride-sea-salt-blend-2kg-pail.html

Then you are not using dead sea salt but at least 95% pure sodium chlorine. The other possibility is that since Arctic is a Canadian company and Canada has outlawed the use of Sodium Bromide in spas or with salt generator systems they ARE selling dead sea salts which contain enough bromide to create a bromine spa and skirting around the law.

This company is a bit more up front and say that dead sea salt creates bromine sanitizer.

https://bluwatertechnology.com/dead-sea-salt-hot-tubs/

Here is some more info on dead sea salt

https://link.springer.com/article/10.1007/s12517-016-2431-9

From the manufacturer:

  • "When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6". 
  • " Salt systems naturally drive pH levels to increase, strive to achieve a balanced pH level"
  • "adding salt to the spas water will increase the pH level. The chlorine that is produced by a salt chlorinator plays a role in the water chemistry of a salt spa. Salt is sodium chloride. When an electric charge is passed through salt water, the sodium chloride is turned into sodium hypochlorite. This is the same kind of chlorine that is sold by the gallon as liquid chlorine. The most important feature of sodium hypochlorite is a high pH. When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6"
  • "It is recommended that calcium be removed from the water in advance, during the fill process with the aid of a pre-filter and when establishing initial correct water chemistry, rather than adding a scale remover after the fact. Calcium readings below 150ppm should be maintained"
  • "545 – 550 mV Spa Boy Optimum Range.
    (Optimum Range is the default factory setting, the
    user may adjust higher if preferred by contacting
    their dealer to have it adjusted. )
    Depending on the water chemistry which will be
    effected by bather load and spa usage, at times
    the ORP value will overshoot or undershoot the
    Optimum Range.
    Note: Using a Drop Test Kit, a 0.5ppm Chlorine
    reading = approximately 550mV"

- My current ORP is ay 850 MV and I keep the FCL high because if you keep it at 545 mv the water gets so cloudy after use and takes forever to get back to normal as they say adding granular chlorine shock is not recommended as it poisons the ORP sensor

- No mention at all of CYA from the manufacturer.  

- What's really confusing me now is the game of achieving TA =50 ppm and then having the PH rise to 7.9 and then lowering the PH and hence lowering the TA and the process starts again with no clear stabilization in my opinion.  Is it possible that saltwater spas with borates (manufacturer makes no reference to borates)  maybe are ok with the low TA ?

-I will let PH go to 8.0and then lower the PH to 7.6 and report back on my success.  Will turn off the aerators

 

Really really appreciate the troubleshooting help!

 

 

 

 

 

 

 

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8 hours ago, westernk said:

 

From the manufacturer:

  • "When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6". 

another 'bucket trick' (false information)

  • " Salt systems naturally drive pH levels to increase, strive to achieve a balanced pH level"

Some truth here, this is achieved by running TA lower than the manufacturer's and industry's recommendation of 80 to 100 ppm and run it at 50 to 70 and don't drop the pH low but run it higher

  • "adding salt to the spas water will increase the pH leve

Blatently false. Salt is sodium chloride. When dissoved in water it has a neutral pH!

"pH of sodium chloride solutions

The pH of a sodium chloride solution remains ≈7 due to the extremely weak basicity of the Cl ion, which is the conjugate base of the strong acid HCl. In other words, NaCl has no effect on system pH[20] in diluted solutions where the effects of ionic strength and activity coefficients are negligible. "

https://en.wikipedia.org/wiki/Sodium_chloride

  • The chlorine that is produced by a salt chlorinator plays a role in the water chemistry of a salt spa. Salt is sodium chloride. When an electric charge is passed through salt water, the sodium chloride is turned into sodium hypochlorite. This is the same kind of chlorine that is sold by the gallon as liquid chlorine. The most important feature of sodium hypochlorite is a high pH.

This is only half the story:

 Unstabilized chlorine sources (liquid chlorine, cal hypo, and lithium hypochlorite) all all alkaline when added to pool water and cause a momentary rise in pH when they dissociate into hypochlorite ions (ClO-) and their respecitive metal ions ( Na+, Ca(2+), or Li+). However, when the hypochlorite , ClO- , ions are reduced to chloride ions , Cl-, in the process of of sanitizing by giving up an oxygen atom (we are ignoring al the side reactions that occur since the reduction of hypochorite is the primary reaction occuring) it is an acidic reaction and therefore the NET result is pH neutral or very close over time. There is a temporary rise on the addition and a reduction of pH as sanitation occurs but the net pH over time is relatively stable.

With organic stabilizied chlorine or bromine (trichor, dichlor, and organic bromine sources found in bromine tabs) the result when added to water is acidic and the result upon reduction to chloride or bromide is also acidic creating a net drop in pH over time.

This is where TA comes into play. When we have a relatively pH neutral system (unstabilized inorganic chlorine sources) the MAIN REASON for pH rise is outgassing of CO2. Period! End of Story! When we add either bicarbonate or carbonate to the water we are purposely overcarbonating the water above it's equilibrium point with the atmosphere. The higher the TA the more carbonation and therefore the faster the outgassing and pH rise. Also, the lower we force the pH we shift the equilibrium of bircarbonate ions toward carbonic acid which, for our purposes, can be thought of as CO2 dissolved in the water. Lower pH means more CO2 means faster outgassing. Therefore, pH stability when using inorganic chlorine sources is achieved by running a LOW TA( 80 ppm or less) and a higher pH (7.6-7.8 ). The carbonate buffer system in pool water is one that causes an upward trend in pH which is useful with acidic chlorine sources as I will explain below.  Addition of 30-50 ppm borate introduces a secondary buffer that helps 'lock' the pH around 7.7 as the upward trend of the bicarbonate buffer and the downward trend of the borate buffer interact. ther are other benefits to borate, most notably its algaestatic properties.

Most common mistake is over carbonating or running a high TA and dropping the pH too low in the mistaken believe that if I drop the pH to 7.2 instead of 7.6 it will be a longer time until I need acid again.

When we have a net acidic system then you want to run a higher TA for the buffer effect to prevent pH crashing but you need to not only monitor pH but also TA since our carbonate buffer will be consumed at a faster rate with the constant addition of acid (similar to how we have to lower TA. We add enough acid to neutralize bicarbonate. The actual reaction is forcing the shift from bicarbonate to carbonic acid. Carbonic acid is NOT measurable as TA. We then need to force this excess carbonic acid out of the water by aeration so it does not convert back to bicarbonate. THIS is the over looked step in lowering TA and explains why TA jumps right back up to where it was initially when pH rises. If we eliminate some of the carbonation then TA will not rise as much with pH. )The constant additon of acid from BOTH our chlorinating chemical AND the reduction of hypochlorite to choride converts the bicarbonate in the water to carbonic acid. IF there is enough aeration to outgas CO2 TA gets 'used up' and pH remains relatively stable. IF the CO2 does not gas off we can get a pH crash, which can happen in covered pools or pools closed for the winter

This is why some CPO courses recommend running TA at 80-100 for inorganic chlorine and 100-120 for organic chlorine and bromine. However, these numbers are not optimum. In the first case 80 ppm is often too high and as low as 50 ppm in high aeration systems (hot tubs, negative edge pools, waterfalls, deck jets, fountains, etc.) is called for. Remember, outgassing of CO2 is the primary cause of pH rise and the more outgassing created by these water features means faster pH rise1 (Now you know why negative edge pools are such a headache when it comes to maintaining the pH when you are not using trichor!)

Trichlor is the most acidic chlorine source and makes the water even more acidic when the hypochlorite ions are reduced to chloride ions. Running a TA as high as 150 ppm is not out of the question in some cases.

In all cases, CH will need to be adjusted to to maintain the calcium saturation index for plaster surfaces and grouted tile pools. There is also some indication that higher calcium can help prevent cobalt spotting in fiberglass but nothing conclusive. Acrylic and vinyl do not need to worry about calcium staturation. If you are worried about corrosion of metal that is solely a function of pH, not calcium.

I hope this explains the chemistry of what's happening in the water. FWIW,  this worked in actual practice so it's not just theory.

(Total disclosure, the ahove is a copy and past from a PM I sent to RDspaguy to answer a question he asked about the same thing (high pH of liquid chlorine). It's a common (and convenient)  misconception in the industry. Convenient because it tends to drive up unnecessary chemical sales!)

  • When the salt chlorinator produces chlorine, it raises the pH of the spas water. Strive to achieve a Low pH level 7.2. pH must not exceed 7.6"
  • "It is recommended that calcium be removed from the water in advance, during the fill process with the aid of a pre-filter and when establishing initial correct water chemistry, rather than adding a scale remover after the fact. Calcium readings below 150ppm should be maintained"
  • "545 – 550 mV Spa Boy Optimum Range.
    (Optimum Range is the default factory setting, the
    user may adjust higher if preferred by contacting
    their dealer to have it adjusted. )
    Depending on the water chemistry which will be
    effected by bather load and spa usage, at times
    the ORP value will overshoot or undershoot the
    Optimum Range.
    Note: Using a Drop Test Kit, a 0.5ppm Chlorine
    reading = approximately 550mV"

- My current ORP is ay 850 MV and I keep the FCL high because if you keep it at 545 mv the water gets so cloudy after use and takes forever to get back to normal as they say adding granular chlorine shock is not recommended as it poisons the ORP sensor

- No mention at all of CYA from the manufacturer.  

Perhaps they know it's a bromine spa and not a chlorine one? Then again, the role of CYA is really not understood in the industry, although its chemistry has been documented since the 60s. John A. Wojtowicz and others have published several technical papers about its use

http://www.poolhelp.com/wp-content/uploads/2017/05/JSPSI_V4N2_pp09-16.pdf

http://www.poolhelp.com/wp-content/uploads/2017/05/JSPSI_V2N1_pp34-41.pdf

http://www.poolhelp.com/wp-content/uploads/2017/05/JSPSI_V4N2_pp17-22.pdf

http://www.poolhelp.com/wp-content/uploads/2019/03/JSPSI-Volume-6-Number-1-pp-06-19-Pickins.pdf

- What's really confusing me now is the game of achieving TA =50 ppm and then having the PH rise to 7.9 and then lowering the PH and hence lowering the TA and the process starts again with no clear stabilization in my opinion.  Is it possible that saltwater spas with borates (manufacturer makes no reference to borates)  maybe are ok with the low TA ?

-I will let PH go to 8.0and then lower the PH to 7.6 and report back on my success.  Will turn off the aerators

bring your TA to 50-70 ppm and wait 24-48 hours, lower your pH to no lower than 7.6 if and only if it is now higher than 7.8 (use an acid demand test to determine how much acid to add) and wait about an hour. Retest both TA and pH. They both should be in range. If TA is still too low bring it up again, readjust pH if needed, etc. However, one time is usually sufficient to get you in range.

Really really appreciate the troubleshooting help!

One last link to a technical paper on bicarbonate, borate, and cyanurate buffer systems in pool water Lots of graphs and if you can understand them you will see what I am saying is true!

http://www.poolhelp.com/wp-content/uploads/2017/05/JSPSI_V3N2_pp34-41.pdf

 

 

 

 

 

 

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6 minutes ago, westernk said:

Regarding Arctic salt :"Natural Sea Salt Water Care. A unique blend of natural Dead Sea Salt and proprietary water clarifiers designed specifically for the Onzen Water Care System

Is there a way to test if what they are selling is sodium chloride or sodium bromid?

Yes, send a sample to a lab for analysis since they don't really publish the information \

From their website:

"Arctic Pure Onzen Sea Salt Blend (Sodium Chloride) is a natural salt water care product.

A unique blend of natural Dead Sea Salt and proprietary water clarifiers designed specifically for the Arctic Spas Onzen and Spa Boy water care systems."

Typical manufacturer doublespeak. If it's sodium chloride it can't be natural dead sea salt since that is not sodium chloride but does contain it along with many other minerals and salts.

If it is a blend of natural dead sea salt and proprietary water clarifies it cannot be sodium chloride since they are admitting it contains other things. It could be a blend of sodium choride and some type of borate (and possibly an inorganic acid to adjust pH) since that is what some other brands of SWG 'mineral blends' are.

 

 

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Awesome.  I have asked an independent lab if they are willing to analyze the salt blend.  Will keep ya'll updated .  Will also follow your procedure of TA up and PH down and will report back.

So I just want to clarify one aspect of sanitization.  With no CYA and a PH of 7.7 to 7.8 and FCL at 5ppm is my sanitizing efficacy materially hampered by the PH being  in this 7.7 to 7.8 range vs if the PH was 7.4 for  example?

 

 

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13 hours ago, westernk said:

So I just want to clarify one aspect of sanitization.  With no CYA and a PH of 7.7 to 7.8 and FCL at 5ppm is my sanitizing efficacy materially hampered by the PH being  in this 7.7 to 7.8 range vs if the PH was 7.4 for  example?

 

it would be about a 20% difference between sanitizing ability at 7.4 vs 7.8 assuming you are running a chlorine system with no CYA and not bromine . If you are truly using dead sea salts you have a bromine tub and CYA is not an issue and pH is not an issue since bromine is effective at a very wide pH range and cannot be stabilized by CYA. If you are running a chlorine system, which would mean your 'dead sea salt blend is really just sodium chloride and perhaps some borax and boric acid and not actual dead sea salts, then the pH does have a small effect but if you add as little as 20 ppm CYA it basically disappears.

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  • 4 weeks later...

the bromide concentration is less than 5 ppm (same as mg/l) and it takes 3 ppm or more to convert a salt system to bromine so it is possible that you have a bromine tub or not. The lab can't accurately determine less than 5 ppm bromide. My guess is that there is not enough bromide ions present to make a difference so you have a salt system and the salt is most certainly NOT dead sea salt!

https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/d/Dead_Sea.htm

"The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride (common salt) with the remainder comprised of various trace elements.

The concentration of sulfate, SO42-, ions is very low, and the bromide ion concentration is the highest of all waters on Earth. Chlorides neutralize most of the calcium ions in the Dead Sea and its surroundings. While in other seas sodium chloride is 97% of the salts, in the Dead Sea the quantity of NaCl is only 12-18%."

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