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Salt Level Constantly Rising Causing Chlorine Generator to Shut Down


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Hi, I'm using a ChlorMaker in a 350gal tub. Initially I set the salt level to 1,750 ppm, the generator indicates Salt Level Normal and works fine for a while. But after a few weeks the device starts to warn of Salt Level High, and then by a month or so shuts down due to Salt Level Exceeds Maximum. At that point I have to drain about 1/3 water and refill with fresh water, and then the generator is happy again. I haven't been able to get through to technical support and am wondering if something I'm adding is driving the salt level up unusually high, or if this is just par for the course with chlorine generators. I use the normal kinds of chemicals like chlorine and oxidizing shock, TA increaser, pH reducer and clarifier. I would appreciate any insights you may have.

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Need to post a full set of test results as a starting point. I do see some possible red flags. What is your TA and why are you raising it? How often do you need to lower pH and what do you lower it to? How often are you adding the MPS shock and why are you doing that if you have a salt water chlorine generator? Do you have a problem with combined chlorine? Liquid chlorine bleach might be a better choice IF you need to shock.

As I said, start with a full set of test results NOT done with test strips.

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Thank you for taking an interest in my problem. Since I've had this spa, I have tried to keep the numbers in line with the chlorine generator manufacturer's recommended parameters; below are those and my current numbers. Per recos here, I have ordered a Taylor K-2006. But for now I'm using a Taylor test kit for pH and chlorine only, an electronic tester for salt, and strips for TA and CH.

               Mfg. Reco       Current
FC             2.0-3.0             2.0
pH             7.2-7.6              7.2
TA            80-120              80
CH           200-400           250
Salt        1500-2000        2600

I check it every day or two and almost always find the pH high (8.0+) and the chlorine low (0.0-0.5). For pH, if TA is blow 80 (about every second or third time), I raise it first, check both again and then add pH reducer as needed. (I have just read here about keeping TA lower than the traditional 80-120 and am considering it.) For low chlorine I hit the boost button, which usually gets it to 3.0, at least for a while. I have college-age kids at home and the spa typically gets used about 8-14 people hours per week.

 

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Do you have any cyanuric acid in your water (chlorine stabilizer). IF not then 2 ppm FC is fine but realize that if you are using the spa during the day and it's receiving sunlight your chlorine will be gone in about 30 minutes or less, depending on bather load. This assumes that your spa is kept covered at all times it's not in use. If it is uncovered and receives sun then CYA is a must! A small amount of cyanuric acid (20-30 ppm) and bumping up the FC to 3-4 ppm. If the spa is uncovered and recieves dunlight throughout the day then a higher CYA and a higher FC level are warranted. This might help explain your low FC levels. The easiest way to add cyanuric acid is to shock the spa with dichlor. I can help you with dosing either dichlor or cyanuric acid if/when you are ready.

Some truths about pH and TA that most manufacturers don't really understand but are based on the actual chemistry of the water:

THE MAIN CAUSE OF pH RISE IN A POOL OR SPA IS OUTGASSING OF CO2.

THE HIGHER THE TA (CARBONATION IN THE WATER), THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WIL RISE.

THE HIGHER THE AERATION OF THE WATER (OZONE SYSTEMS, SALT WATER SANITIZER SYSTEMS, AIR INJECTORS,  AERATION FROM YOUR JETS, 24 HOUR CIRCULATION ON HIGH SPEED, ETC.) THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE LOWER YOU PLACE THE pH THE FASTER IT WILL RISE (YOU ARE CONVERTING MORE BICARBONATE IONS, WHICH IS WHAT TA IS,  INTO CARBONIC ACID, ESSENTIALLY CO2 DISSOLVED IN THE WATER. THE HIGHER THE CO2 IN THE WATER THE FASTER IT WILL OUTGAS TO ACHIEVE EQUALIBRIUM WITH THE ATMOSPHERE.)

This post explains how outgassing causes pH rise and how to minimize it.

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

A few things you can do for better pH stability:

Lower your TA to 50-70 ppm

Don't lower your pH below about 7.6. Wait unti it is above 7.8 before lowering it again (pH should be checked daily or as close as possible. TA weekly until you know your spa and how often it changes then monthly is probably often enough)

Add 30-50 PPM borate as a secondary pH buffer that will help hold your pH at around 7.7 - 7.8 . This is particularly helpful in salt systems that, by nature, constantly aerate the water in the cell by production of hydrogen bubbles on the anode. You can use specialty products like Proteam Gentle Spa, SpaPure Simply Soft,Salinity Borate Plus (specifically made for salt systems and sold by Pinch a Penny but really no different from the other products),  Proteam Supreme Plus, Bioguard Optimizer plus, etc. All these produces are pH neutral. You can also use boric acid, which will slightly lower pH when added, 20 mule team borax (sodium tetraborate decahydrate), or such products at Proteam Supreme or Bioguard Optimizer (original formulas), which are sodium tetraborate pentahydrate. All forms of borax (decahydrate and pentahydrate) are alkaline and will require the addition of acid to offset the pH rise. The only difference between the decahydrate and the (expen$ive) pentahydrate is the number of attached water molecules (Penta means 5 attached water, deca meeans 10). This will cause a slight difference in dosing for the same borate level but, even so, the decahydrate is much more cost effective if you decide to go this route. (This is the way I do my  pool and spa, btw.)

BEST way to test borate level is with LaMotte Borate Test strips. they have a color change from pink to tan that is much easier to read than the strips from Aaquchek, Hach, and Taylor which are all made by Hach and have color changes of very close shades of tan that are almost impossible to read, IMHO.

Some info on borate:

https://aquamagazine.com/features/the-basics-boric-acid-and-sodium-borates.html

 

Too high a salt level will either shut down the generation of chlorine or burn out your cell, depending on whether your system has a high salt/low salt shut off or not. Realize that any electrolyte in the water will add to your salt reading since this is merely a measure of conductivity in the water and the higher the electrolyte level, the higher the conductivity and therefore the higher your "salt" will read when read with an electronic tester. This will include:

Sodium Bicarbonate (TA increaser/baking soda, both are exactly the same),

Sodium Bisulfite (dry acid, pH reducer which also adds sulfates which can potentially damage salt cells, Muriatic acid, while much more difficult to use, is a better choice, IMHO since it breaks down into hydrogen ions and chloride ions and that is exactly the same thing being produced in your salt cell in a salt system. . Given the small size of your tub I would get the 14% acid sold at Home depot (half strength) rather than the 31.4% acid normally sold for pools and spas since it will make dosing easier and will fume less.),

Sodium Carbonate (pH increaser/washing soda, once again same thing) which will raise TA along with pH and is really only necessary in system that are using trichlor tabs since it is extremely acidic and prone to making the pH/TA "crash"),

Borate (inconsequential when dosed in a 30-50 ppm range),

Cyanuric Acid/CYA (also inconsequential up to around 80 ppm).

The only way to actually measure sodium chloride content in your water is with a chemical test such as the Taylor K 1766 (dichromate/silver nitrate titration) or with the Hach or Aquachek salt titrator test strips (silver nitrate based). The titrator strips are much easier to use at the expense of some precision but you MUST follow the instructions and give enough time 5 minutes or longer) for the test to work. The Taylor test is precise to +/- 200 ppm which is certainly close enough but is tricky to do right, to say the least!

Hope this helps.

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If you are using an electronic salt meter or a TDS meter then any ions in the water will increase conductivity. Fun fact, there is not any real difference between a TDS meter and a salt meter other than the calibration of the scale. They both measure electrical conductivity. IF you want to know the actual sodium chloride content of the water you will need to use a chemical test or titrator strip. Under most normal operating conditions there is a correlation between salt level and conductivity so salt meters do work in most cases but there are exceptions, especially if someone keeps dumping in baking soda and dry acid or there is a malfunction of the salt cell which is another distinct possibility.

 

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Wow, you've given me a lot to think about. Every time I think I have this stuff down, something blows up and I have to learn something new to deal with it. It's kind of fun though.

This weekend it's time for another drain and fill. The borate (Leisure Time - Spa Balancer pH Balance Plus), LaMotte Borate and Aquachek salt titrator test strips I ordered should be in by then and I might pick up some Muriatic acid as well. (I may need an excuse splip from you for all the stuff I'm buying to give to my wife. But she's the one who wanted the thing anyway!)

My approach this time around will be to add everything esle that's need besides salt first, and then add as little salt as possible only at the end. And my hope is that the bromide causes less chemicals to be needed to control the pH.

Getting to RDspaguy's comment, it seems that just about everything I'm putting in there is an elctrolite, potentially adding to the conductivity of the water and leading to the cell shutting down. The top four additives I'm using are TA increaser, pH reducer, MPS and dichlor, which are all salts. Makes me wonder why everyone is not having the same problem as I am with the chlorine generator.

I'll let you know how it goes.

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15 hours ago, meh07 said:

TA increaser, pH reducer

why? You want your TA at 50-70 ppm. Even a bit lower than 50 is OK if you are having a problem with pH rise. You raise your TA, the pH goes up, you add dry acid, pH and TA go down, your raise your TA, pH goes up, you add dry acid, pH and TA go down, your raise your TA, pH goes up, you add dry acid, pH and TA go down...

Does this sum up what you've been doing?

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16 hours ago, meh07 said:

Leisure Time - Spa Balancer pH Balance Plus

Mostly boric acid but it does contain some sodium carboante which might raise your TA!

http://www.appatek.com/SDS/Leisure Time SDS/PH Balance Plus.pdf

You might have to bring TA back down after dosing to 30-50 ppm borate. When you use it up just get some boric acid instead, it will also save you money. Add it after adjusting TA. I will slighly lower your pH but it will rise with aeration.

https://www.chemistrystore.com/Chemicals_A-F-Boric_Acid.html

Also, if you DO need to ever raise TA use baking soda (from the grocery store). It is EXACTLY the same chemical as TA increaser, sodium bicarbonate, aka sodium hydrogen carbonate

 

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25 minutes ago, waterbear said:

You raise your TA, the pH goes up, you add dry acid, pH and TA go down, your raise your TA, pH goes up, you add dry acid, pH and TA go down, your raise your TA, pH goes up, you add dry acid, pH and TA go down...

Stop! I'm getting dizzy!🤪

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I purchased the Spa Balancer pH Balance Plus after I read on this forum about the benefits, and before I started this post. It was hard enough for me to find something that had mostly just boric acid in it, and I'd love to know how you found the safety sheet. I've been hesitant to go straight to the raw chemicals due to all the warnings about products being "specially formulated for home use" stuff, being a newbie and all.

BTW, this product aside, does city water have any sodium bicarbonate, or something like it, in it? If not, I'm wondering why so many people seem to have too much of it when they are the ones controlling how much goes in in the first place?

 

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  • 2 weeks later...

Following up for those interested. I had great success with adding salt last and in increments. I started by adding all the other startup chemicals, checking and adjusting levels as I went. (And yes, waterbear, you were correct – my plain tap water had TA 90 and CH 137.)

Then I added 2/3 of the suggested salt amount and the SWG indicated low salt. So, I added ¼ of the previous amount, and bingo, the magic blue light came on. The SWG is now creating so much chlorine that I’ve had to turn it down from 6 to 3 (also helped by the new presence of CYA, I imagine.)

Also, the effect of adding borate has been excellent. My TA and pH had been all over the place, but since initial adjustment it hasn’t budged from ~135 and 7.6 in two weeks.

Thanks for the help!

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  • 4 months later...

This sounds a lot like the problems I am having. I know that ph will rise over time with my salt spa, but I go to bed withy ph at 7.2 and in the morning it is 7.8 to 8.2 after running filtration and the salt cell. I have tried to keep my TA between the recommended 80-100, but I've noticed a couple of times that my ph didn't rise and it was when my TA was 40-50. I'm just a little hesitant to keep my TA that low as I have read that it may be corrosive. Any thoughts?

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It's not 'corrosive'. You (and many professionals also) seem to confuse water with a low calcium saturation index (calculated from the CH, TA, pH, Temperature, and some other minor factors with water being 'corrosive'. IF you have a plaster surface pool or spa water can be aggressive and affect the plaster but it has no bearing on acrylic, fiberglass, or vinyl poos and spas not does it have any effect on pool pumps and heaters. If the pH is too low (below 7.0) THEN water can be corrosive to such things as pump seals, plaster surfaces, and metal parts in the pool or spa. but it has nothing to do with TA unless you are using trichlor, which is extremely acidic, so you need to run a high TA to compensate and force the pH upward. However, a salt generator produces sodium hypochlorite (bleach) which is net pH neutral (basic when produced but acidic when it is consumed)

6 hours ago, CanadaJack said:

I've noticed a couple of times that my ph didn't rise and it was when my TA was 40-50

BINGO! Give the man a cigar!

Read this:

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

Now go back and read it again!

The reason your pH is rising fast is because your TA is TOO HIGH. End of story.  Your salt system is a major source of aeration (in addition to the jets, air injectors, ozone, and bubbblers found in spas)  since hydrogen gas bubbles are produced at the cathode of your salt cell.

 

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