Can Super Chlorinating With Bleach Be Used To Shock A Swg Pool?

[Gavin]

I read somewhere that you have to use an oxidizer like Cal Hypo to shock an SWG pool. but why would a SWG pool need to be shocked? doesn't the cell destroy CC?

Thanks

[chem geek]

If you properly maintain the appropriate FC/CYA level in your SWG pool or in any residential pool, for that matter, then you normally do not need to shock your pool. However, many people do not use sufficient FC/CYA levels so they need to shock to prevent nascent algae growth or to oxidize organics more quickly. You can read Water Balance for SWGs for more info, but basically for SWG pools the FC should be at least 4.5% of the CYA level at all times, so most people just target an FC that is 5% of the CYA level. Manually dosed pools use a higher target (FC that is 7.5% of the CYA level). This all assumes good circulation in the pool.

Nevertheless, if you want to super-chlorinate for any reason, such as an unusually high bather load or a dead animal in the pool or vomit, etc. then yes you can use any source of chlorine and using bleach or chlorinating liquid would add only chlorine (and salt) without any Cyanuric Acid (CYA) from Trichlor or Dichlor or Calcium Hardness (CH) from Cal-Hypo.

As for CC, in a properly maintained pool, there is continual shocking from the chlorine since it is always present and oxidizing your bather waste. The CC is usually <= 0.2 ppm and is once in a while <= 0.4 ppm. However, this depends a lot on whether the pool is indoors or outdoors and on the bather load, amount of leaves and other organic material, etc. Outdoor residential pools can usually keep their CC quite low. You are right that an SWG should help with this, but even manually dosed pools can have low CC. Indoor pools often have more difficulty, however, probably due to the lack of UV from sunlight and the inadequate air circulation which removes volatile disinfection by-products.

[Gavin]

If you properly maintain the appropriate FC/CYA level in your SWG pool or in any residential pool, for that matter, then you normally do not need to shock your pool. However, many people do not use sufficient FC/CYA levels so they need to shock to prevent nascent algae growth or to oxidize organics more quickly. You can read Water Balance for SWGs for more info, but basically for SWG pools the FC should be at least 4.5% of the CYA level at all times, so most people just target an FC that is 5% of the CYA level. Manually dosed pools use a higher target (FC that is 7.5% of the CYA level). This all assumes good circulation in the pool.

Nevertheless, if you want to super-chlorinate for any reason, such as an unusually high bather load or a dead animal in the pool or vomit, etc. then yes you can use any source of chlorine and using bleach or chlorinating liquid would add only chlorine (and salt) without any Cyanuric Acid (CYA) from Trichlor or Dichlor or Calcium Hardness (CH) from Cal-Hypo.

As for CC, in a properly maintained pool, there is continual shocking from the chlorine since it is always present and oxidizing your bather waste. The CC is usually <= 0.2 ppm and is once in a while <= 0.4 ppm. However, this depends a lot on whether the pool is indoors or outdoors and on the bather load, amount of leaves and other organic material, etc. Outdoor residential pools can usually keep their CC quite low. You are right that an SWG should help with this, but even manually dosed pools can have low CC. Indoor pools often have more difficulty, however, probably due to the lack of UV from sunlight and the inadequate air circulation which removes volatile disinfection by-products.

Thanks Chem geek as usual you are most knowledgeable! Excellent info! Thanks! I've actually bookmarked a lot of your replies. I've been using bleach a lot instead of Cal Hypo. in fact I want to sell what Cal hypo I got left and just use bleach. my CYA is high and I'm able like you recommend to keep FC at around 8% of CYA. this seems to be working at keeping algae away and also seems to keep CC @ 0.

[Gavin]

seems to be a bit of a debate going on about SWG pools....

what are your thoughts?

[chem geek]

If you want to read more about the downsides to SWG systems, read this blog. Note however that most people are happy with their SWG systems. So the reality is that there are real problems and most of these can be mitigated. The main problem was that the industry overall was not fully disclosing of the problems, but that is now changing to some degree. Also, some of the problems seem to have been dependent on location since the bigger problems with stone needed a certain amount of splash-out and evaporation cycles so would not apply as much to cooler climates or ones with periodic rain that would wash away the salt. Bottom line, be educated about the pros and cons so you can prevent problems up-front. Don't use soft stones unless you seal them.

[Gavin]

If you want to read more about the downsides to SWG systems, read this blog. Note however that most people are happy with their SWG systems. So the reality is that there are real problems and most of these can be mitigated. The main problem was that the industry overall was not fully disclosing of the problems, but that is now changing to some degree. Also, some of the problems seem to have been dependent on location since the bigger problems with stone needed a certain amount of splash-out and evaporation cycles so would not apply as much to cooler climates or ones with periodic rain that would wash away the salt. Bottom line, be educated about the pros and cons so you can prevent problems up-front. Don't use soft stones unless you seal them.

Thanks. That makes sense. I guess there are the pros and cons with all systems of chlorination. I read in Pool School that the best way to Chlorinate was using a SWG then came the floater. however the floater needs to be tethered so as not to hang around the ladder and rust it.

[chem geek]

I don't think the Pool School would recommend using a floater (except for a short-time such as on vacation), which normally has Trichlor, since that would increase CYA over time. After an SWG, normally what is recommended is either bleach or chlorinating liquid, either added manually or possibly via The Liquidator or a peristaltic pump.

[Gavin]

I don't think the Pool School would recommend using a floater (except for a short-time such as on vacation), which normally has Trichlor, since that would increase CYA over time. After an SWG, normally what is recommended is either bleach or chlorinating liquid, either added manually or possibly via The Liquidator or a peristaltic pump.

I think you are right. Then after the bleach the floater. they don't recommend putting trichlor pucks in the skimmer. so floater is better when you don't have the time to keep adding bleach?

[quantumchromodynamics]

I recommend against a floater. You should not be using chlorinated cyanuric acid tablets (trichlor) for routine chlorination, in most cases.

If you want to use trichlor, the only way I recommend feeding them is by way of an off-line feeder. The introduction point for the chlorine should be downstream of any other equipment to avoid damaging the equipment with the low pH and high chlorine levels. The Cyanuric Acid level must not be allowed to go higher than 80 ppm.

[Gavin]

I recommend against a floater. You should not be using chlorinated cyanuric acid tablets (trichlor) for routine chlorination, in most cases.

If you want to use trichlor, the only way I recommend feeding them is by way of an off-line feeder. The introduction point for the chlorine should be downstream of any other equipment to avoid damaging the equipment with the low pH and high chlorine levels. The Cyanuric Acid level must not be allowed to go higher than 80 ppm.

Thanks. what happens if CYA goes higher than 80ppm? I have 120-150 CYA and FC: 14 and pH is now down to 7.2

[chem geek]

It just makes the pool harder to manage, but you can do so with the higher FC levels you have (I wouldn't let the FC get much below 10 ppm in order to prevent algae growth). Over time, you should dilute the water to lower the CYA and that clearly means no use of any stabilized chlorine (Trichlor or Dichlor).

[Gavin]

It just makes the pool harder to manage, but you can do so with the higher FC levels you have (I wouldn't let the FC get much below 10 ppm in order to prevent algae growth). Over time, you should dilute the water to lower the CYA and that clearly means no use of any stabilized chlorine (Trichlor or Dichlor).

Yes I've been just using bleach and also diluting the water every week. slowly will het the CYA down.

[Swim 'N Save USA]

I read somewhere that you have to use an oxidizer like Cal Hypo to shock an SWG pool. but why would a SWG pool need to be shocked? doesn't the cell destroy CC?

Thanks

There is a special "no-chlor" shock specifically designed for salt water generator pool systems. If you need any further assistance, feel free to call our service department at (727) 686-9219 / (813) 639-8890 or visit us on the web at www.swimnsaveusa.com. We have an on-site "do it yourself" guide as well as tips, advice, sales, promotions & giveaways.

[chem geek]

You are no doubt talking about No-Chlor which is just potassium monopersulfate and is NOT specifically designed for salt pools. It can be used in any pool, but is a lot more expensive to use than just superchlorinating with chlorine, such as bleach or chlorinating liquid. Also, if you properly maintain an appropriate FC/CYA ratio, there is usually no need to shock a pool at all.

[Swim 'N Save USA]

You are no doubt talking about No-Chlor which is just potassium monopersulfate and is NOT specifically designed for salt pools. It can be used in any pool, but is a lot more expensive to use than just superchlorinating with chlorine, such as bleach or chlorinating liquid. Also, if you properly maintain an appropriate FC/CYA ratio, there is usually no need to shock a pool at all.

chem geek, you are absolutely correct, you can use them on salt, chlorine & bromine based sanitized pools, however, most pool owners select the salt water alternative due to a number of reasons, one of the most common is the absence of the "chlorine" smell. Using "no chlor" will in fact keep the need for chlorine type products not be placed into your pool. In all circumstances, it is really up to the pool owner as to the decision of using cal-hypo, no-chlor, or simply super chlorinating using the mix of muriatic acid/liquid chlorine, or tablets. Of course, super chlorinating or cal-hypo is the cheaper alternative

[chem geek]

In a saltwater chlorine generator (SWG) pool, if one maintains a Free Chlorine (FC) level that is 5% of the Cyanuric Acid (CYA) level, then not only is there minimal to no chlorine smell, but there is no need to shock the pool at all under normal circumstances. The same can be said for manually dosed (i.e. non-SWG) pools where the FC is maintained at a minimum of 7.5% of the CYA level.

[Gavin]

In a saltwater chlorine generator (SWG) pool, if one maintains a Free Chlorine (FC) level that is 5% of the Cyanuric Acid (CYA) level, then not only is there minimal to no chlorine smell, but there is no need to shock the pool at all under normal circumstances. The same can be said for manually dosed (i.e. non-SWG) pools where the FC is maintained at a minimum of 7.5% of the CYA level.

kudos! this is the method I like. never need to shock or use an algaecide.

however someone told me that I should be keeping my chlorine below a certain amount as this is law. Is there a law that prohibits maintaining a pools chlorine level above a certain amount?

Thanks.

[Swim 'N Save USA]

In a saltwater chlorine generator (SWG) pool, if one maintains a Free Chlorine (FC) level that is 5% of the Cyanuric Acid (CYA) level, then not only is there minimal to no chlorine smell, but there is no need to shock the pool at all under normal circumstances. The same can be said for manually dosed (i.e. non-SWG) pools where the FC is maintained at a minimum of 7.5% of the CYA level.

kudos! this is the method I like. never need to shock or use an algaecide.

however someone told me that I should be keeping my chlorine below a certain amount as this is law. Is there a law that prohibits maintaining a pools chlorine level above a certain amount?

Thanks.

As far as I know of, there is no "law" governing the use of chlorine levels in a pool. This is something you would have to check in your particular area, however, I also don't know why anyone would want an abnormally high concentration of chlorine as this does just as much damage to your pool surface as having too little sanitizer with an algae infestation.

[Gavin]

In a saltwater chlorine generator (SWG) pool, if one maintains a Free Chlorine (FC) level that is 5% of the Cyanuric Acid (CYA) level, then not only is there minimal to no chlorine smell, but there is no need to shock the pool at all under normal circumstances. The same can be said for manually dosed (i.e. non-SWG) pools where the FC is maintained at a minimum of 7.5% of the CYA level.

kudos! this is the method I like. never need to shock or use an algaecide.

however someone told me that I should be keeping my chlorine below a certain amount as this is law. Is there a law that prohibits maintaining a pools chlorine level above a certain amount?

Thanks.

As far as I know of, there is no "law" governing the use of chlorine levels in a pool. This is something you would have to check in your particular area, however, I also don't know why anyone would want an abnormally high concentration of chlorine as this does just as much damage to your pool surface as having too little sanitizer with an algae infestation.

http://wiki.answers.com/Q/What_is_the_chlo...n_swimming_pool

amount of FC needed to sanitize and keep algae away is calculated from a % of the CYA. If CYA is high then more FC is required. However from what I've gathered if an algaecide is used less FC is needed. Only problem with that is copper build up and possible staining. Might as well go with an mineral ion solution one time (chlorine free). Just best make sure you have a really accurate copper test kit and keep pH on the lower side.

[PoolManPete]

In a saltwater chlorine generator (SWG) pool, if one maintains a Free Chlorine (FC) level that is 5% of the Cyanuric Acid (CYA) level, then not only is there minimal to no chlorine smell, but there is no need to shock the pool at all under normal circumstances. The same can be said for manually dosed (i.e. non-SWG) pools where the FC is maintained at a minimum of 7.5% of the CYA level.

kudos! this is the method I like. never need to shock or use an algaecide.

however someone told me that I should be keeping my chlorine below a certain amount as this is law. Is there a law that prohibits maintaining a pools chlorine level above a certain amount?

Thanks.

As far as I know of, there is no "law" governing the use of chlorine levels in a pool. This is something you would have to check in your particular area, however, I also don't know why anyone would want an abnormally high concentration of chlorine as this does just as much damage to your pool surface as having too little sanitizer with an algae infestation.

http://wiki.answers.com/Q/What_is_the_chlo...n_swimming_pool

amount of FC needed to sanitize and keep algae away is calculated from a % of the CYA. If CYA is high then more FC is required. However from what I've gathered if an algaecide is used less FC is needed. Only problem with that is copper build up and possible staining. Might as well go with an mineral ion solution one time (chlorine free). Just best make sure you have a really accurate copper test kit and keep pH on the lower side.

Thats only if you used a copper based algecide. Copper sulfate is used as an algaecide in the treatment of surface waters such as reservoirs, lakes and ponds. It should not be used in swimming pools At the pH of a typical swimming pool and in the presence of chlorine or other oxidizing agents, copper (from copper sulfate, natural sources or corrosion of heaters) can and will cause staining and discoloration of pool surfaces and hair. Of course there are people that use it in pools and have no problems. But why risk when there are other better products.

[chem geek]

As far as I know of, there is no "law" governing the use of chlorine levels in a pool. This is something you would have to check in your particular area, however, I also don't know why anyone would want an abnormally high concentration of chlorine as this does just as much damage to your pool surface as having too little sanitizer with an algae infestation.

For residential pools, there are no laws to my knowledge preventing you from doing anything you want with your pool in terms of water chemistry. As for product labeling, the EPA has an FC limit of 4 ppm for drinking water so they prevent EPA registered pesticides such as swimming pool disinfectants with chlorine from giving any range higher than 4 ppm based on FIFRA labeling rules.

For commercial or public pools, there are regulations in each state or that vary by county health department. Typically these allow for larger ranges of chlorine. Many allow as high as 10 ppm FC; some have lower limits -- all are OK for higher FC for shocking and the limits only apply to when bathers are in the water.

None of these, to my knowledge, has any inkling of the chlorine/CYA relationship. The FC is relevant if you were to drink the water since it is the total chlorine capacity that is relevant in that case, but for the rate of disinfection, oxidation of skin, hair, organics, etc., and prevention of algae, it is primarily the hypochlorous acid level that is relevant and that is roughly proportional to the FC/CYA ratio.

[Gavin]

As far as I know of, there is no "law" governing the use of chlorine levels in a pool. This is something you would have to check in your particular area, however, I also don't know why anyone would want an abnormally high concentration of chlorine as this does just as much damage to your pool surface as having too little sanitizer with an algae infestation.

For residential pools, there are no laws to my knowledge preventing you from doing anything you want with your pool in terms of water chemistry. As for product labeling, the EPA has an FC limit of 4 ppm for drinking water so they prevent EPA registered pesticides such as swimming pool disinfectants with chlorine from giving any range higher than 4 ppm based on FIFRA labeling rules.

For commercial or public pools, there are regulations in each state or that vary by county health department. Typically these allow for larger ranges of chlorine. Many allow as high as 10 ppm FC; some have lower limits -- all are OK for higher FC for shocking and the limits only apply to when bathers are in the water.

None of these, to my knowledge, has any inkling of the chlorine/CYA relationship. The FC is relevant if you were to drink the water since it is the total chlorine capacity that is relevant in that case, but for the rate of disinfection, oxidation of skin, hair, organics, etc., and prevention of algae, it is primarily the hypochlorous acid level that is relevant and that is roughly proportional to the FC/CYA ratio.

Thanks for the info.

so I guess keep FC at the right % of CYA we are continually oxidizing which keeps the water looking really nice and clear.

I've been researching the PoolSan mineral ion system and it seems people tend to over oxidize their pools as it looks better but then staining often results. still reading up but plan on trying it. however I'd feel better getting a better copper test kit like one from Taylor. I have the PoolSan test kit but its really really hard to see where the copper is with it. colors on the chart are so faint.

[chem geek]

so I guess keep FC at the right % of CYA we are continually oxidizing which keeps the water looking really nice and clear.

I've been researching the PoolSan mineral ion system and it seems people tend to over oxidize their pools as it looks better but then staining often results. still reading up but plan on trying it. however I'd feel better getting a better copper test kit like one from Taylor. I have the PoolSan test kit but its really really hard to see where the copper is with it. colors on the chart are so faint.

Yes, you've got that exactly correct. Oxidation of bather waste occurs continuously so long as there is FC in the water. The rate is roughly determined by the FC/CYA ratio.

Mineral ion systems do not oxidize anything. All they do is prevent algae growth (mostly copper) and assist with some sanitation (mostly silver), but the kill rates are far lower than for chlorine with regard to disinfection of pathogens. For something that takes 1-2 minutes for chlorine to kill 99% (with CYA in the water, so at an FC/CYA ratio of 10%), it takes silver ion around 10 minutes and copper ion around 20 minutes. There is no question that copper ions are effective at killing algae and preventing its growth (though you still need chlorine to clear a pool that already has an algae bloom or cloudy water), HOWEVER the level of copper ions needed to achieve this is close to its level of staining pool surfaces, especially if the pH gets too high.

So generally it is not a good idea to use metal ion systems unless you have a way of measuring and controlling their concentration and very carefully manage and control the pH (and TA and CYA since either of those getting to high can also precipitate different kinds of metal stains).

I don't understand why you want a metal ion system. You can both sanitize the pool and prevent algae growth with chlorine alone by simply maintaining an appropriate FC/CYA ratio. Even with a 10% ratio, this has the same active chlorine concentration as around 0.1 ppm FC with no CYA so is quite low. If you really wanted to have a supplemental algicide so that you could lower the chlorine level, then using PolyQuat 60 weekly will probably let you have an FC/CYA ratio below 5%, perhaps in the 2-3% range which is quite low. That would be like 1 ppm FC with 30-50 ppm CYA or 2 ppm FC with 70-100 ppm CYA.

[Gavin]

so I guess keep FC at the right % of CYA we are continually oxidizing which keeps the water looking really nice and clear.

I've been researching the PoolSan mineral ion system and it seems people tend to over oxidize their pools as it looks better but then staining often results. still reading up but plan on trying it. however I'd feel better getting a better copper test kit like one from Taylor. I have the PoolSan test kit but its really really hard to see where the copper is with it. colors on the chart are so faint.

Yes, you've got that exactly correct. Oxidation of bather waste occurs continuously so long as there is FC in the water. The rate is roughly determined by the FC/CYA ratio.

Mineral ion systems do not oxidize anything. All they do is prevent algae growth (mostly copper) and assist with some sanitation (mostly silver), but the kill rates are far lower than for chlorine with regard to disinfection of pathogens. For something that takes 1-2 minutes for chlorine to kill 99% (with CYA in the water, so at an FC/CYA ratio of 10%), it takes silver ion around 10 minutes and copper ion around 20 minutes. There is no question that copper ions are effective at killing algae and preventing its growth (though you still need chlorine to clear a pool that already has an algae bloom or cloudy water), HOWEVER the level of copper ions needed to achieve this is close to its level of staining pool surfaces, especially if the pH gets too high.

So generally it is not a good idea to use metal ion systems unless you have a way of measuring and controlling their concentration and very carefully manage and control the pH (and TA and CYA since either of those getting to high can also precipitate different kinds of metal stains).

I don't understand why you want a metal ion system. You can both sanitize the pool and prevent algae growth with chlorine alone by simply maintaining an appropriate FC/CYA ratio. Even with a 10% ratio, this has the same active chlorine concentration as around 0.1 ppm FC with no CYA so is quite low. If you really wanted to have a supplemental algicide so that you could lower the chlorine level, then using PolyQuat 60 weekly will probably let you have an FC/CYA ratio below 5%, perhaps in the 2-3% range which is quite low. That would be like 1 ppm FC with 30-50 ppm CYA or 2 ppm FC with 70-100 ppm CYA.

wow Chem you are really a wealth of info! Many thanks!

I understand the PoolSan problems and I know that some pools pH can swing up and down quite a bit making staining a real probability in these mineral ion pools.

I just don't understand the active chlorine amount. If I have a pool with CYA of 100 and I keep FC at 7.5%+ of CYA or above 7.5ppm isn't the active chlorine 7.5ppm or above? how is it lower? isn't active chlorine the same as the FC? I don't understand.

[chem geek]

When I refer to "active chlorine" I am referring to the hypochlorous acid concentration since that is what does the sanitation and most of the oxidation. The chlorine bound to CYA (technically called chlorinated isocyanurates) are minimally effective sanitizers and oxidizers (about 100 times slower than hypochlorous acid as far as oxidation of a standard organic as described here). At a pH of 7.5, the 7.5 ppm FC with 100 ppm CYA there is only 0.031 ppm as hypochlorous acid, 0.033 ppm as hypochlorite ion, and 7.436 ppm as a variety of different chlorinated isocyanurate compounds (that is, chlorine bound to CYA). This has roughly the same oxidation and sanitation power as having only 0.07 ppm FC with no CYA.

In other words, when you have CYA in the water, there is very little real chlorine available doing the real work, but fortunately most pathogens need only a very low concentration of chlorine to get killed quickly. Most of the chlorine is in reserve and will get released from being bound to CYA as the active real chlorine gets used, but reaction rates are based on the hypochlorous acid concentration and not on the amount in reserve. You can read the introductory sections of the classic 1974 paper that defined the equilibrium constants between hypochlorous acid and the chlorine bound to CYA here.