Cal Hypo Raises Ph But Does 99% Stabalized Granula Chlorine Raise Ph?

[Gavin]

just wondering if the stabilized granular also raises pH? I've used Cal Hypo and that raises pH. never tested the TA though...would that also be raised using Cal Hypo or stabilized granular? I'm using desert granular which is stabilized.

Thanks.

[chem geek]

The Cal-Hypo only raises the pH when added to increase the Free Chlorine (FC) level, but as the FC level drops back down this is an acidic process that exactly compensates so that the pH goes back down to where you started. If you are finding the pH to rise anyway, then that's most likely due to your TA being too high and the pH rise is caused by carbon dioxide outgassing. If by stabilized granular you mean Dichlor, then that starts out close to pH neutral, but the chlorine usage/consumpation is acidic so the net result is a drop in pH unless you have carbon dioxide outgassing. If you meant Trichlor instead (which also comes in a granular form, though is normally in puck form), this is acidic upon addition so is very net acidic.

Just keep in mind the side effects of using these chemicals:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm

For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.

For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

A little simple math will show you that you can increase your CYA or CH levels quite quickly even at low daily chlorine usage. If you used bleach or chlorinating liquid, then you would not increase either CYA nor CH.

Pools are intentionally over-carbonated in order to provide a pH buffer and to protect plaster, but TA is a SOURCE of rising pH itself due to carbon dioxide outgassing so as counter-intuitive as it seems, lowering the TA when using hypochlorite sources of chlorine results in greater pH stability. To keep the saturation index near zero you would increase the CH or the target pH somewhat to compensate. I suggest you take a look at the Pool School to learn much more about how you can maintain your pool with minimal cost.

For my own 16,000 gallon pool shown here and here I only use 12.5% chlorinating liquid from my local pool store (who reuse the bottles, so better than recycling) plus a small amount of Muriatic Acid added once a month or so. My chlorine usage is low at around 1 ppm FC per day due to a mostly opaque pool safety cover though the pool is used every day for 1-2 hours and more on weekends. The chemical cost during the swim season is only $17 per month. The pool is algae-free in spite of usually having 2000-3000 ppb phosphates -- yes, you can keep your pool in good shape without phosphate removers, algicides, clarifiers, etc.

[Gavin]

The Cal-Hypo only raises the pH when added to increase the Free Chlorine (FC) level, but as the FC level drops back down this is an acidic process that exactly compensates so that the pH goes back down to where you started. If you are finding the pH to rise anyway, then that's most likely due to your TA being too high and the pH rise is caused by carbon dioxide outgassing. If by stabilized granular you mean Dichlor, then that starts out close to pH neutral, but the chlorine usage/consumpation is acidic so the net result is a drop in pH unless you have carbon dioxide outgassing. If you meant Trichlor instead (which also comes in a granular form, though is normally in puck form), this is acidic upon addition so is very net acidic.

Just keep in mind the side effects of using these chemicals:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm

For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.

For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

A little simple math will show you that you can increase your CYA or CH levels quite quickly even at low daily chlorine usage. If you used bleach or chlorinating liquid, then you would not increase either CYA nor CH.

Pools are intentionally over-carbonated in order to provide a pH buffer and to protect plaster, but TA is a SOURCE of rising pH itself due to carbon dioxide outgassing so as counter-intuitive as it seems, lowering the TA when using hypochlorite sources of chlorine results in greater pH stability. To keep the saturation index near zero you would increase the CH or the target pH somewhat to compensate. I suggest you take a look at the Pool School to learn much more about how you can maintain your pool with minimal cost.

For my own 16,000 gallon pool shown here and here I only use 12.5% chlorinating liquid from my local pool store (who reuse the bottles, so better than recycling) plus a small amount of Muriatic Acid added once a month or so. My chlorine usage is low at around 1 ppm FC per day due to a mostly opaque pool safety cover though the pool is used every day for 1-2 hours and more on weekends. The chemical cost during the swim season is only $17 per month. The pool is algae-free in spite of usually having 2000-3000 ppb phosphates -- yes, you can keep your pool in good shape without phosphate removers, algicides, clarifiers, etc.

Thanks. I really like the CYA/FC calculation to keep algae away. It really works well and I prefer this method instead of using an algicide.

I'm using Trichlor granular to shock.

Now I accidentally lowered my pH to 7.0 and my TA to 60. I guess I need to add some baking soda to bring these numbers up. Can I add 4lbs a day or should I just add 2lbs per day? I know its recommended to add small amounts of baking soda to raise levels. The pool calculator says to add 9lbs of baking soda.

[chem geek]

I'm using Trichlor granular to shock.

Now I accidentally lowered my pH to 7.0 and my TA to 60. I guess I need to add some baking soda to bring these numbers up. Can I add 4lbs a day or should I just add 2lbs per day? I know its recommended to add small amounts of baking soda to raise levels. The pool calculator says to add 9lbs of baking soda.

Why are you using Trichlor granular to shock? First of all, you normally do not need to shock your pool if you are consistently maintaining an appropriate FC/CYA ratio. I didn't have to shock my pool at all last year except on spring opening (when I accidentally let the chlorine get to zero as the water was warming up and had a bacterial conversion of CYA into ammonia). Unless you intentionally want to increase your CYA level, you should use bleach or chlorinating liquid for shocking your pool (when needed), not stabilized chlorine nor Cal-Hypo. Shocking is often done in stabilized pools because the chlorine levels are too low since the FC/CYA ratio drops as the CYA climbs. Bather waste is continually getting oxidized in low bather load residential pools and you normally do not need to shock unless there is an extreme event such as unusually high bather load or a release of vomit or a lot of urine or a dead animal in the pool, etc. Have you been measuring the Combined Chlorine (CC) level? If it's <= 0.5 ppm and you don't have one of these extreme events then don't shock the pool. In my own pool, it's almost always <= 0.2 ppm and only once in a while might be <= 0.4 ppm.

Do not use baking soda. That is for raising TA, not for raising pH, though it will have some effect on the pH. If you want to raise the pH with no change in TA, then aerate the water (turn the returns up, pump on high, add a water fountain, etc.). If you want to raise the pH with half the rise in TA compared to pH Up products, then use 20 Mule Team Borax. You can use The Pool Calculator to calculate approximate dosing, but add half the amount and retest after an hour of mixing so that you don't overshoot.

You probably don't need to raise your TA directly at all. When you raise the pH using Borax, the TA will rise as well, probably up to 70 ppm which might be good enough for your pool if you want a more stable pH over time. You basically adjust your TA until your pH is fairly stable and then adjust CH to compensate for the saturation index.

[Gavin]

I'm using Trichlor granular to shock.

Now I accidentally lowered my pH to 7.0 and my TA to 60. I guess I need to add some baking soda to bring these numbers up. Can I add 4lbs a day or should I just add 2lbs per day? I know its recommended to add small amounts of baking soda to raise levels. The pool calculator says to add 9lbs of baking soda.

Why are you using Trichlor granular to shock? First of all, you normally do not need to shock your pool if you are consistently maintaining an appropriate FC/CYA ratio. I didn't have to shock my pool at all last year except on spring opening (when I accidentally let the chlorine get to zero as the water was warming up and had a bacterial conversion of CYA into ammonia). Unless you intentionally want to increase your CYA level, you should use bleach or chlorinating liquid for shocking your pool (when needed), not stabilized chlorine nor Cal-Hypo. Shocking is often done in stabilized pools because the chlorine levels are too low since the FC/CYA ratio drops as the CYA climbs. Bather waste is continually getting oxidized in low bather load residential pools and you normally do not need to shock unless there is an extreme event such as unusually high bather load or a release of vomit or a lot of urine or a dead animal in the pool, etc. Have you been measuring the Combined Chlorine (CC) level? If it's <= 0.5 ppm and you don't have one of these extreme events then don't shock the pool. In my own pool, it's almost always <= 0.2 ppm and only once in a while might be <= 0.4 ppm.

Do not use baking soda. That is for raising TA, not for raising pH, though it will have some effect on the pH. If you want to raise the pH with no change in TA, then aerate the water (turn the returns up, pump on high, add a water fountain, etc.). If you want to raise the pH with half the rise in TA compared to pH Up products, then use 20 Mule Team Borax. You can use The Pool Calculator to calculate approximate dosing, but add half the amount and retest after an hour of mixing so that you don't overshoot.

You probably don't need to raise your TA directly at all. When you raise the pH using Borax, the TA will rise as well, probably up to 70 ppm which might be good enough for your pool if you want a more stable pH over time. You basically adjust your TA until your pH is fairly stable and then adjust CH to compensate for the saturation index.

Thanks Chem geek. Much appreciated.

I read somewhere to shock once a month. i guess I didn't need to and should not have done. plus I used stabilized not a good move. well now i need to get my pH up and TA up a little. I will use the Borax. thanks. I'll go now to pool calculator and see how much Borax I need. thanks again!

[precision]

I agree- using trichlor as a shock is not only very expensive but not nec. If you keep an eye on the important things as the chem geek mentioned- shocking will be required less frequently and you can also get away with a cal-hypo or liquid (lythium based) shock- far less expensive with less side effects when used properly

[Gavin]

I agree- using trichlor as a shock is not only very expensive but not nec. If you keep an eye on the important things as the chem geek mentioned- shocking will be required less frequently and you can also get away with a cal-hypo or liquid (lythium based) shock- far less expensive with less side effects when used properly

I guess if CYA is 0 then shocking a green pool with trichlor like "desert granular" which is 99% chlorine is the way to go.

[chem geek]

You can do that if you want to, but if the CYA is zero and you've got a lot of algae you are going to need a lot of chlorine to get rid of it in any event. Using Trichlor or Dichlor powder for shocking will add some CYA which will help protect the chlorine from sunlight, but it should definitely not be overdone. Generally speaking, it is better to use chlorinating liquid or bleach to kill off an algae bloom. See this link for example of clearing algae after spring opening.

Normally the CYA isn't zero in a pool if you've been using stabilized chlorine. Algae won't consume CYA (though there are some bacteria that can, but that's another story).

[Gavin]

You can do that if you want to, but if the CYA is zero and you've got a lot of algae you are going to need a lot of chlorine to get rid of it in any event. Using Trichlor or Dichlor powder for shocking will add some CYA which will help protect the chlorine from sunlight, but it should definitely not be overdone. Generally speaking, it is better to use chlorinating liquid or bleach to kill off an algae bloom. See this link for example of clearing algae after spring opening.

Normally the CYA isn't zero in a pool if you've been using stabilized chlorine. Algae won't consume CYA (though there are some bacteria that can, but that's another story).

Thanks for the reply.

I prefer using liquid chlorine however this pool really had 0 CYA and I wanted the chlorine to stay in the pool longer. Here is a before pic and after...

btw CYA is now at 60. also had tons of sludge on the bottom and also had to give the filter a good cleaning. had some CC after clearing but got rid of it by shocking with bleach.

I couldn't have done it without the help from you guys. Many Thanks!