Shock Dont Work!

[E Z]

have a 48000 gal gunite pool and added 6 gallons of namco (blue shield ) liquid shock treatment whick has 12.5% sodium hypochlorite per gallon. An hour later i got a 0 reading of free chlorine. It seem as if this product had no effect on my pool? this is the second time i have tried this season. All other indicators seem to be ok (i tested the strips on the spa and they showed a chlorine reading I use a powder form of chlorine for the spa). the only issue that i had when opening the pool was a high ph level i used muric acid to bring it down. Is the problem with the product or my pool?

[chem geek]

In theory, 6 gallons of 12.5% chlorinating liquid in 48,000 gallons should raise the Free Chlorine (FC) level by 7.7 ppm. There are several possibilities. One is that you are using a DPD chlorine test (the one where you measure of intensity of red color) and that this bleaches out above 10 ppm FC so perhaps the chlorine level is actually high. Another possibility is that you have a strong chlorine demand in the pool either from nascent algae growth or from leftover ammonia if your Cyanuric Acid (CYA) level dropped over the winter due to degradation by soil bacteria (in the pool) if you let your pool go. Finally, the chlorine you have could be bad. The easiest way to test is to take a very small amount of your chlorinating liquid and add one fluid ounce to one gallon of tap water (filtered water would be better) and then mix. Then take one fluid ounce of that and add it to a fresh gallon of tap (or filtered) water. This combination is a dilution of 16,384 where 12.5% should result in about 7.6 ppm FC. The tap water could have either 1 ppm FC or 1 ppm CC on its own, but anything higher would be from your chlorinating liquid. If you don't measure at least 5 ppm Free Chlorine (FC), then your chlorine source is bad. That would be unusual as you should be able to see the chlorinating liquid as looking yellow/green and it should smell like strong bleach.

Are you just opening your pool after closure over the winter? If so, did you let the pool go and not add any chlorine or algaecide during the winter? My guess is that your CYA could have degraded to ammonia and that can take a LOT of chlorine to break down (oxidize). If you have a good test kit, you should post other numbers of pH, TA, CYA and CH as well as Combined Chlorine (CC). A good test kit is the Taylor K-2006 which you can get at a good online price here or the TF100 from tftestkits.com here which has 36% more volume so is comparably priced "per test".

Richard

[E Z]

Richard,

Thank You for you help !

I tested the chlorine with the two gallons and i got a high reading which tells us that th chlorine is good. i had just opened the pool after the winter and it was covered with a hard canvas cover. i took the water on friday to a pool store to get it tested and here are the results.

fc 0.2ppm

tc 2.1 ppm

cc 1.9 ppm

ph 7.5

hardness 90 ppm

alkalinity 80 ppm

ca 10 ppm

copper 0.07

after receiving these results i added 25 lb of hardness and 4 lb of ca.

any suggestions ?

In theory, 6 gallons of 12.5% chlorinating liquid in 48,000 gallons should raise the Free Chlorine (FC) level by 7.7 ppm. There are several possibilities. One is that you are using a DPD chlorine test (the one where you measure of intensity of red color) and that this bleaches out above 10 ppm FC so perhaps the chlorine level is actually high. Another possibility is that you have a strong chlorine demand in the pool either from nascent algae growth or from leftover ammonia if your Cyanuric Acid (CYA) level dropped over the winter due to degradation by soil bacteria (in the pool) if you let your pool go. Finally, the chlorine you have could be bad. The easiest way to test is to take a very small amount of your chlorinating liquid and add one fluid ounce to one gallon of tap water (filtered water would be better) and then mix. Then take one fluid ounce of that and add it to a fresh gallon of tap (or filtered) water. This combination is a dilution of 16,384 where 12.5% should result in about 7.6 ppm FC. The tap water could have either 1 ppm FC or 1 ppm CC on its own, but anything higher would be from your chlorinating liquid. If you don't measure at least 5 ppm Free Chlorine (FC), then your chlorine source is bad. That would be unusual as you should be able to see the chlorinating liquid as looking yellow/green and it should smell like strong bleach.

Are you just opening your pool after closure over the winter? If so, did you let the pool go and not add any chlorine or algaecide during the winter? My guess is that your CYA could have degraded to ammonia and that can take a LOT of chlorine to break down (oxidize). If you have a good test kit, you should post other numbers of pH, TA, CYA and CH as well as Combined Chlorine (CC). A good test kit is the Taylor K-2006 which you can get at a good online price here or the TF100 from tftestkits.com here which has 36% more volume so is comparably priced "per test".

Richard

[chem geek]

If your pool is really 48,000 gallons which is quite large, then 25 pounds of Calcium Chloride (anhydrous) will raise the CH by 56 ppm (25 pounds of Calcium Chloride Dihydrate would raise the CH by 43 ppm). 4 pounds of Cyanuric Acid will raise the CYA (what the pool store calls CA) by 10 ppm. With a plaster/gunite pool, you'll need more hardness, but before worrying about that, your high CC along with your rapid chlorine consumption means you've either got lots of algae or pollen or something consuming the chlorine or you've got lots of ammonia in the water, possibly from CYA getting converted to ammonia over the winter by bacteria.

If the pool is green or cloudy, then it's algae. If it's relatively clear, then it's likely to be ammonia. Did you have a higher CYA level when you closed the pool? I suspect so and that it got converted to ammonia. It's going to take a LOT of chlorine to remedy this. If the pool store can measure ammonia levels, then have them do that. Otherwise, you can take a bucket of pool water and do tests adding small amounts (teaspoons) of chlorine until it starts to hold the FC level over at least one hour. Then you can scale up that amount of chlorine for the size of your pool -- it's going to be a LOT, unfortunately, unless I'm wrong about what's going on.

[E Z]

Richard,

The pool water was clear when i opened it after the winter and it is still clear.i am not sure what the reading on the cya was before it was closed for the winter .What is the typical amount of amonia (ppm) that should be in the pool? i will see if a local pool store can test for it. The only way to get rid of the amonia is to drown it in chlorine? Should i first worry about the cc before trying to get the hardness and the cya into acceptable ranges? The pool size is a 23x50 3 1/2 TO 8 1/2 deep. Wht type of chlorine would you use for such a situation?

If your pool is really 48,000 gallons which is quite large, then 25 pounds of Calcium Chloride (anhydrous) will raise the CH by 56 ppm (25 pounds of Calcium Chloride Dihydrate would raise the CH by 43 ppm). 4 pounds of Cyanuric Acid will raise the CYA (what the pool store calls CA) by 10 ppm. With a plaster/gunite pool, you'll need more hardness, but before worrying about that, your high CC along with your rapid chlorine consumption means you've either got lots of algae or pollen or something consuming the chlorine or you've got lots of ammonia in the water, possibly from CYA getting converted to ammonia over the winter by bacteria.

If the pool is green or cloudy, then it's algae. If it's relatively clear, then it's likely to be ammonia. Did you have a higher CYA level when you closed the pool? I suspect so and that it got converted to ammonia. It's going to take a LOT of chlorine to remedy this. If the pool store can measure ammonia levels, then have them do that. Otherwise, you can take a bucket of pool water and do tests adding small amounts (teaspoons) of chlorine until it starts to hold the FC level over at least one hour. Then you can scale up that amount of chlorine for the size of your pool -- it's going to be a LOT, unfortunately, unless I'm wrong about what's going on.

[chem geek]

There should normally be no ammonia in the water. If your CYA did get converted to ammonia by bacteria in the water over the winter (and that happens sometimes), then yes, it takes lots of chlorine to get rid of it. Dilution will of course reduce it as well.

The CC you are measuring is probably from the ammonia combining with the chlorine, if indeed it's ammonia in the water. You can certainly adjust the Calcium Hardness (CH) perhaps up to around 250 ppm, but don't worry about the CYA right now since a higher CYA will just make the chlorine oxidation of ammonia take longer. You want some CYA in the water so the chlorine won't go away quickly in sunlight, but you've already got some and that's probably enough for now.

By the way, if you do have ammonia in the pool, then the chlorine combining with it should smell like "bad" chlorine smell (i.e. monochloramine). Do you notice any such odor?

Your pool measurements would indeed indicate a roughly 51,000 gallon pool, so 48,000 may well be correct. That's a large pool!

Richard

[E Z]

i retested the water at the pool place and got this reading.

FC 0.0

CC 0.7

ph 7.3

ch 240

ak 80

cya 15

phosphate 1000 ?

they gave me some chem to kill the phosphate and said thats whats eating the fc and cc.

i found a test kit for ammonia at a pet store and tested the water it showed a reading of 4ppm.

what should i do?

There should normally be no ammonia in the water. If your CYA did get converted to ammonia by bacteria in the water over the winter (and that happens sometimes), then yes, it takes lots of chlorine to get rid of it. Dilution will of course reduce it as well.

The CC you are measuring is probably from the ammonia combining with the chlorine, if indeed it's ammonia in the water. You can certainly adjust the Calcium Hardness (CH) perhaps up to around 250 ppm, but don't worry about the CYA right now since a higher CYA will just make the chlorine oxidation of ammonia take longer. You want some CYA in the water so the chlorine won't go away quickly in sunlight, but you've already got some and that's probably enough for now.

By the way, if you do have ammonia in the pool, then the chlorine combining with it should smell like "bad" chlorine smell (i.e. monochloramine). Do you notice any such odor?

Your pool measurements would indeed indicate a roughly 51,000 gallon pool, so 48,000 may well be correct. That's a large pool!

Richard

[chem geek]

The higher phosphate level will have algae grow more quickly and that will consume some chlorine, but not at the rate you are seeing. Chlorine alone can kill and keep away algae at reasonable chlorine levels (minimum FC of 7.5% of the CYA level) up to a phosphate level of around 3000 ppb. So I don't believe the pool store is correct about this. Also, the fact that you measure 4 ppm ammonia would indicate that the problem is ammonia, not algae growth. Your water is also clear and your CYA level isn't very high (if it was, then chlorine would be slower at killing algae).

I'll bet that phosphate remover set you back in your wallet -- that stuff isn't cheap! Since you've already bought it, you can use it as an algaecide for the future. Now on to the ammonia. Assuming the ammonia 4 ppm measurement is a measurement of nitrogen (see if the test kit says it measures "ammonia-nitrogen" or "NH3-N" or something like that), then it will take cumulatively about 40 ppm (minimum of 30 ppm) of Free Chlorine (FC) to get rid of the rest of the ammonia.

As a reasonable experiment, if you want to try using the phosphate remover first and see if that makes any difference in the chlorine holding (and can have your water rechecked for phosphates by the pool store after you've used the remover), then that would be useful to know if the pool store is right about this. Otherwise, if you think you can get your money back on the phosphate remover, you can try taking it back for a refund -- up to you. I'm guessing that it won't help and that adding chlorine will still get used up quickly. If so, then just keep adding chlorine and I'll bet that when you've cumulatively added about 40 ppm FC then your pool will start holding chlorine again. Note that I am not saying to raise the FC to 40 ppm -- just add chlorine in 10 ppm FC doses, wait for it to drop significantly (probably in an hour), then retest to see near zero FC and add the next 10 ppm of chlorine.

Let us know how things go as the only way to validate the chemical theory in real pools is with real experiences such as yours.

Richard

[E Z]

decided to go with the chlorine...

added 26 gal of liquid chlorine 12.5% and its showing a very high FC after four hours )))(starting to wonder if i added to much:) ) i will leave the pool open to the sun for the next few days untill it all burns off. Richard thank for all your help..you were on the money..

The higher phosphate level will have algae grow more quickly and that will consume some chlorine, but not at the rate you are seeing. Chlorine alone can kill and keep away algae at reasonable chlorine levels (minimum FC of 7.5% of the CYA level) up to a phosphate level of around 3000 ppb. So I don't believe the pool store is correct about this. Also, the fact that you measure 4 ppm ammonia would indicate that the problem is ammonia, not algae growth. Your water is also clear and your CYA level isn't very high (if it was, then chlorine would be slower at killing algae).

I'll bet that phosphate remover set you back in your wallet -- that stuff isn't cheap! Since you've already bought it, you can use it as an algaecide for the future. Now on to the ammonia. Assuming the ammonia 4 ppm measurement is a measurement of nitrogen (see if the test kit says it measures "ammonia-nitrogen" or "NH3-N" or something like that), then it will take cumulatively about 40 ppm (minimum of 30 ppm) of Free Chlorine (FC) to get rid of the rest of the ammonia.

As a reasonable experiment, if you want to try using the phosphate remover first and see if that makes any difference in the chlorine holding (and can have your water rechecked for phosphates by the pool store after you've used the remover), then that would be useful to know if the pool store is right about this. Otherwise, if you think you can get your money back on the phosphate remover, you can try taking it back for a refund -- up to you. I'm guessing that it won't help and that adding chlorine will still get used up quickly. If so, then just keep adding chlorine and I'll bet that when you've cumulatively added about 40 ppm FC then your pool will start holding chlorine again. Note that I am not saying to raise the FC to 40 ppm -- just add chlorine in 10 ppm FC doses, wait for it to drop significantly (probably in an hour), then retest to see near zero FC and add the next 10 ppm of chlorine.

Let us know how things go as the only way to validate the chemical theory in real pools is with real experiences such as yours.

Richard

[chem geek]

decided to go with the chlorine...

added 26 gal of liquid chlorine 12.5% and its showing a very high FC after four hours )))(starting to wonder if i added to much:) ) i will leave the pool open to the sun for the next few days untill it all burns off. Richard thank for all your help..you were on the money..

26 gallons of 12.5% chlorinating liquid in 48,000 gallons would raise the FC by 67.7 ppm which is very high (yes, you added too much -- the 10 ppm FC at a time would have been better). You are lucky your pool didn't get cloudy and/or produce scale since the pH would have shot way up to around 8.6 from the chlorine and the saturation index would have been over +0.9. However, within the hour, the chlorine would have oxidized the ammonia and brought back down the pH a little. If I assume that the 4 ppm ammonia-nitrogen was correct and that this consumed about 30 ppm FC, then the pH would have dropped to around 8.4 and you'd have about 38 ppm FC left over and the saturation index would be +0.8. Still pretty high. So yes, let the sun burn that off, which it should do somewhat quickly since the CYA level isn't really high. You might have the FC drop by a third in one day -- maybe almost half if you are in a very intense sunny area (though we're not in June yet). The pH will drop as the chlorine gets broken down from the sun and should get back to around 7.5 to 7.8 depending on what FC level you let it get to.

In the future, use The Pool Calculator to figure out the dosing of chemicals for your pool.

Richard

[E Z]

Richard

Its very sunny outside today in jersey so hopefully the Fc will burn off, I tested the water for ammonia this morning and its totaly clear..i am still getting a very high FC and PH level and i presume there is nothing to do but wait it out untill it all burns off. do you think that the high ph for the next few days can damage the plaster finish?

I use a nature 2 cartridge during the pool season to have low chlorine in the water. (i havent installed it yet becouse my water was not balanced). what is your feeling about the product? is it safe to keep the fc at 1% as they suggest?

decided to go with the chlorine...

added 26 gal of liquid chlorine 12.5% and its showing a very high FC after four hours )))(starting to wonder if i added to much:) ) i will leave the pool open to the sun for the next few days untill it all burns off. Richard thank for all your help..you were on the money..

26 gallons of 12.5% chlorinating liquid in 48,000 gallons would raise the FC by 67.7 ppm which is very high (yes, you added too much -- the 10 ppm FC at a time would have been better). You are lucky your pool didn't get cloudy and/or produce scale since the pH would have shot way up to around 8.6 from the chlorine and the saturation index would have been over +0.9. However, within the hour, the chlorine would have oxidized the ammonia and brought back down the pH a little. If I assume that the 4 ppm ammonia-nitrogen was correct and that this consumed about 30 ppm FC, then the pH would have dropped to around 8.4 and you'd have about 38 ppm FC left over and the saturation index would be +0.8. Still pretty high. So yes, let the sun burn that off, which it should do somewhat quickly since the CYA level isn't really high. You might have the FC drop by a third in one day -- maybe almost half if you are in a very intense sunny area (though we're not in June yet). The pH will drop as the chlorine gets broken down from the sun and should get back to around 7.5 to 7.8 depending on what FC level you let it get to.

In the future, use The Pool Calculator to figure out the dosing of chemicals for your pool.

Richard

[chem geek]

Richard

Its very sunny outside today in jersey so hopefully the Fc will burn off, I tested the water for ammonia this morning and its totaly clear..i am still getting a very high FC and PH level and i presume there is nothing to do but wait it out untill it all burns off. do you think that the high ph for the next few days can damage the plaster finish?

I use a nature 2 cartridge during the pool season to have low chlorine in the water. (i havent installed it yet becouse my water was not balanced). what is your feeling about the product? is it safe to keep the fc at 1% as they suggest?

The high pH is mostly a concern for scaling which would make the plaster finish rough. You can't drop the pH too much because as the chlorine gets broken down from sunlight the pH will drop further and if the pH gets too low then corrosion of metal and etching of plaster are possible, though probably wouldn't happen very quickly. See how the FC drops over a day. If it isn't dropping fast enough, you can get a chlorine neutralizer product from the pool store to speed it up.

Nature2 is a separate issue. If you had that cartridge installed or otherwise had copper and/or silver ions in the water, then staining of the plaster is a real possibility as high pH precipitates the metal ions from Nature2. That's the main reason not to use Nature2 in pools, especially in plaster pools. If you carefully manage your pH, then Nature2 can be seen as a supplemental algaecide, similar to adding PolyQuat 60 weekly or using a phosphate remover. This would let you have a somewhat lower chlorine level of perhaps half the normal manual dosing level, so closer to what an SWG pool uses. So perhaps with Nature2 you could keep a minimum chlorine level that was around 3-4% of the CYA level and in any event not lower than 1-2 ppm FC depending on bather load. However, keep in mind that even at the recommended manually dosed target of an FC that is 10% of the CYA level, that this is technically equivalent to an FC level of only 0.1 ppm if no CYA were present. In other words, it's already a very small amount of actual disinfecting and oxidizing chlorine. In a properly maintained pool, you shouldn't smell the chlorine nor have many effects from it. Part of the problem comes from the swings in FC from manual dosing, but you can get around this by using The Liquidator which is talked about in this thread.

Richard

[E Z]

The ph seems to have gone down to the 7.8 range however i am still showing a high fc rate (the strips i use only go up to 10ppm) i was supprised to see the combined level of chlorine on the strip was showing in the 8 range. why would that be if there is still so much fc?

Regarding the liquidator can it be used with the nature 2? lats year when i used the nature 2, I kept the pool at 1ppm thru the summer and shocked it with liquid chlorine once every two weeks. do you think using the liquidator i will not need to shock any more? with the nature 2 what would be the ideal level of cya?

[chem geek]

When the chlorine combines with ammonia it forms monochloramine which gets measures as Combined Chlorine. This then breaks down using up additional chlorine. However, your measured CC on the test strip may just be an anomaly from the very high FC level (i.e. a test error) since the breakdown of ammonia should happen rather quickly, in an hour or so, at your relatively low CYA level (assuming that measurement was done accurately). You really need to get yourself your own good test kit as I described in my first post. That's the only way you can really know what is in your water.

As for The Liquidator and Nature2 -- yes they are compatible. The Liquidator is nothing more than an automatic dosing system for chlorinating liquid or bleach. As for needing to shock, if the pool was at a normal FC level (closer to 10% of the CYA level), then typically one doesn't need to shock at all or perhaps only when there is unusually high bather load (such as after a pool party). However, it's not as clear if you keep the FC level lower as to whether a shock will be needed -- the purpose of shocking is to oxidize organics (and specifically combined chlorine) that may build up but if the FC is maintained then there is continual breakdown of organics and you never get behind. You could just monitor the CC level and if it's always near zero, then you don't need to shock. I hardly ever shock and my CC levels are almost always zero (<= 0.2 ppm).

As for CYA level, that depends on the rate of chlorine breakdown from sunlight. Start with 30 ppm CYA and see what happens when you start with 2 ppm FC at the start of the day. If it drops below 1 ppm FC (and you'll need the good test kit that measures to within 0.2 ppm FC for this test), then increase the CYA level to 50 ppm and try again. If the FC drops by less than half its amount in a day, then you've got enough CYA in the water, especially at your low FC levels. If you end up with 50 ppm CYA, then I'd make your FC target 1.5-2.0 ppm instead of 1.0-1.2 ppm FC with 30 ppm CYA.

Richard

[ddove]

Hi I'm a new member and I have a similar problem. My pool store says I have a chlorine demand caused by pollen turning into ammonia. I had the pool tested 5/17/08 and here are the readings. Saturation index.1, tds 1000, cya 0, total chlorine 4.7 free chlorine 0, ph 8.1, total akalinity 107, total hardness 88. I have a 26,000 gallon inground gunite pool, and it is clear. I use silks sticks for chlorine, and burnout extreme 2 as a shock. I added 7 pints of muriatic acid and 2 lbls of stabalizer and plan to add 2 more pounds today. We have had a little rain so I'm not sure how this is going to effect the pool. The pool store is recommended 60lbs of shock and to test for free chlorine every 3 hours. I'm looking for something less extreme and expensive. Please help!!! Thanks

Dave

[chem geek]

Hi I'm a new member and I have a similar problem. My pool store says I have a chlorine demand caused by pollen turning into ammonia. I had the pool tested 5/17/08 and here are the readings. Saturation index.1, tds 1000, cya 0, total chlorine 4.7 free chlorine 0, ph 8.1, total akalinity 107, total hardness 88. I have a 26,000 gallon inground gunite pool, and it is clear. I use silks sticks for chlorine, and burnout extreme 2 as a shock. I added 7 pints of muriatic acid and 2 lbls of stabalizer and plan to add 2 more pounds today. We have had a little rain so I'm not sure how this is going to effect the pool. The pool store is recommended 60lbs of shock and to test for free chlorine every 3 hours. I'm looking for something less extreme and expensive. Please help!!! Thanks

Dave

Dave,

First of all, get your own good test kit such as the Taylor K-2006 test kit you can get at a good online price here or the TF100 test kit from tftestkits.com here with the latter having 36% more volume of reagents so comparable in price "per test". I don't trust the pool store numbers, especially the CYA of 0 since Silk Sticks are Trichlor and for every 10 ppm FC that they add, they also increase CYA by 6 ppm. The Burnout Extreme is Cal-Hypo and for every 10 ppm FC that it adds, it also increases Calcium Hardness (CH) by 7 ppm.

Your Calcium Hardness (CH) level is too low for a gunite (plaster) pool and the pool store is irresponsible only measuring "Total Hardness" instead of "Calcium Hardness". Again, get your own test kit as you can test for everything except metals and phosphates -- the only tests your pool store can do if and when you need them.

Though it is true that lots of pollen will increase chlorine demand, it will not convert to ammonia (at least not directly measurable that way). For pollen, one usually uses a skimmer sock to help get collect it and get rid of it before it hits your filter.

Again, get your own test kit and then you can see what needs to be done.

Richard