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Free Chlorine 0

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On 5/31 I opened our semi-inground pool. Added water, cleaned etc. Took the water to a pool place to be tested, and followed there advice. Well as of today, after shocking 6x. My fc is 0, tc 14.9 cyanuric acid 0, ph 7.6,total alkalinity is 210,total hardness is 80. What am i doing wrong???Why is my free chlorine 0. The pool is perfectly clear.....Please help..Thanks

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Assuming your numbers are correct, there are several problems. First, is that without any Cyanuric Acid (CYA) in the pool, the chlorine will break down in sunlight -- losing up to half every 30 minutes in direct noontime sun. So some CYA is needed in the pool (not much -- getting to 30 ppm should be enough for now). If your TC is truly about 15 ppm with 0 FC, then that means the Combined Chlorine (CC) is 15 ppm. It could be that you have a lot of ammonia in your pool and adding chlorine is just creating monochloramine which registers as CC. You can get an inexpensive ammonia test at a pet/fish/aquarium store to see if there is still ammonia left.

You get rid of ammonia and monochloramine by further addition of chlorine, but to know how much is needed you need to measure the ammonia level. It takes about 10x the ammonia amount (measured as ppm Nitrogen) plus around 1x the CC amount (measured as ppm Cl2) to get rid of both.

I suspect you had CYA in the pool before you closed it for the winter and then let the pool go over the winter. Soil bacteria that got into the pool can convert CYA into ammonia. To prevent this in the future, see if you can sanitize the pool over the winter or at least close it by first shocking with chlorine and then adding PolyQuat 60 algaecide and then opening up the pool as early as possible, at least as far as adding chlorine is concerned.

Richard

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Thanks Richard for responding. We're still shocking with no change. We closed the pool with a pool closing kit, not sure if the water was tested before closing. We used GLB'S pool closing kit, which has oxybrite,Algimycin winter and sequa-sol. The water wasn't too bad when we opened,just a little cloudy, with a couple of leaves that got under the cover. Never had a problem with cya last year. Anyway i will get the ammonia level tested and get back to you with results. Pool is still crystal clear and we've been running filter 12+ hours a day. Pool size 12x24 4 1/2 feet deep, aprox 9000 gal. We would like to get the kids in pool before summer so any help is greatly appreciated. We're definitely feeling frustrated with this. Thanks again-Debbie

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Pool stores can vary a lot in the quality of their testing so I strongly suggest you get your own good test kit, either the Taylor K-2006 kit you can get at a good online price here or the TF100 test kit from tftestkits.com here with the latter kit having 36% more volume of reagents so is comparably priced "per test".

I also forgot to mention that your Total Alkalinity (TA) is very high. Depending on the source of chlorine you use, you may find a strong tendency for the pH to rise over time. If you use Trichlor tabs/pucks, which are very acidic, then this might not be noticeable, but continued usage of such pucks/tabs will increase the CYA level over time. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. The procedure to lower the TA is described in this post, but that's something you can tackle later after resolving your issue of FC not holding.

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Well, I got the ammonia test kit and next door was another pool store. So I had them test my water. They recommended non-chlorine shock, they said I had too much chlorine in pool, a chlorine lock or something like that. Here are my new readings cya and fc still 0, Tot chl 8.5,ph 7.5, ta 111, th 59. The ammonia tested 8.0, nice dark green. What does this mean? Pool still looks nice and clear. Yes I know I need my own test kit, I'm going to try to go to Leslie's Pools to get there test kit Chlorine fas-dpd svc. or order the one you recommended. Thanks again-Debbie

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Debbie,

An ammonia reading of 8 ppm is extremely high. The pool store recommendation of non-chlorine shock is certainly an alternative for getting rid of the ammonia, but it is more expensive than using chlorinating liquid or unscented bleach to accomplish the same thing. Nevertheless, if that 8 ppm ammonia reading is correct (and is in "ppm Nitrogen" units, as is standard with ammonia measurements), then it will take a cumulative amount of Free Chlorine (FC) of nearly 80 ppm to get rid of it and that's almost 13 gallons (17 96-ounce jugs) of 6% unscented bleach or 6-1/2 gallons of 12.5% chlorinating liquid for 10,000 gallons (more for a larger pool; less for a smaller one). The equivalent amount of non-chlorine shock would be 30 pounds per 10,000 gallons which is pretty darn expensive. And I'm not even counting the 8.5 ppm CC that is there, though that doesn't take nearly as much chlorine to get rid of.

So again, if that ammonia measurement is correct, then it will take an extraordinary amount of chlorine or non-chlorine shock to get rid of it. The only other option is to drain and refill the pool (through continuous dilution or multiple partial drain/refill or using the "sheet" or "silage bag" method).

Yes, the Leslie's FAS-DPD service kit is like the Taylor K-2006, but usually you can only get it online -- if your Leslie's has it in stock, then that's great.

The very real question comes up with how in the heck did you get so much ammonia in the pool in the first place? If you "let a pool go" over the winter and don't maintain a chlorine level in it, then it is possible for soil bacteria to convert the Cyanuric Acid (CYA) in the pool into ammonia. Such bacteria would do so at a rate of converting every 10 ppm CYA into 3.3 ppm ammonia so in your pool did approximately 25 ppm CYA or so "disappear" over the winter? Or did someone accidentally drop some ammonia into the pool?

Richard

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Richard, I repeated the test and got the same answer 8.0 ppm. Not sure what happened either. We closed it with chemicals and when we opened it, the pool really didn't look bad, slightly cloudy. As far as maintaining during the winter, the pool is closed and covered. Are we supposed to be doing something else during the winter? We did add some water when we opened it, like 5-6 inches. It's been clear since we shocked it but the levels have been off. So what should I do now?? Get 17 jugs of unscented bleach? Do I put it in all at once or over a period of days?? Then how long before I test it again? I called a Leslies and they say they have the test kit in and the supermarket has the bleach on sale tomorrow. So I'll be heading out tomorrow morning. I really don't know why the ammonia level is so high. We've always bought our chemicals from a pool place and did what they told us to do. Does the shock pump up the ammonia level, because that and 3inch slo-dissolving stablized chlorine tablets and some Super Blue Crystal Clear water polisher are all we used. Thanks again -Debbie

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Debbie,

Unless the pool freezes or you live in an area where the water in the pipes can freeze during the winter, you can periodically add chlorine to it and run the pump to mix it, probably just once a month, and keep it sanitary over the winter. If you live in a freezing climate, then you obviously can't be running the pump so you close the pool by shocking with chlorine, letting the chlorine drop a bit, then adding a heavy dose of PolyQuat 60 algaecide. Then, try opening in the spring as early as possible before the water warms up.

If I were you, I'd make sure that the chlorine will work by doing a bucket test. If you fill a 2-gallon bucket with pool water, then 2 teaspoons of 6% bleach will add 80 ppm FC to that bucket so try that amount, mix, wait about 30 minutes, then test for FC. If none is measured, add one more teaspoon and try again. If at some point you start to measure FC, then you'll know this will work, but if it takes more than 4 teaspoons then that's going to be a LOT of chlorine for the pool.

The shock (which is probably Dichlor) and the tablets which are Trichlor will raise the Cyanuric Acid (CYA) level over time, but that does not directly increase ammonia. The ammonia most likely came from bacteria that grew in the pool during the winter and used the CYA as "food" and converted it to ammonia. This is not uncommon in pools that are "let go" over the winter, but usually the resulting ammonia level isn't as high -- perhaps your pool was covered so tightly that the ammonia was unable to outgas (it's a little volatile).

Richard

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Hi Richard, ok, I brought the test kit from Leslie's pool. Before I tried the bucket test I tested the water. Results fc 2,ph 7.2, ta 130, cya 0,ammonia 4 and tc was a little darker than 5. So what do I do now? I than tried the bucket test, only on the fc and it went up to fc 3 close to fc 5 and ammonia .5 with 2 tsp of bleach. So I guess my main concern is the cya and ammonia. I'm not sure what to do with those levels. As far as the winter, I live in New York, so we definitely turn off the pump etc. Thanks- Debbie

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Richard, scratch the bucket test, with the fc I didn't wait a 1/2 hour, I did for the ammonia. I got so into being a chemist, I messed up.Oops!-Debbie

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Richard, scratch the bucket test, with the fc I didn't wait a 1/2 hour, I did for the ammonia. I got so into being a chemist, I messed up.Oops!-Debbie

Don't worry about it. Nevertheless, with the initial drop in ammonia and some FC remaining from your quick measurement it does seem like your initial numbers were in the correct ballpark. So you can clear your pool with lots of chlorine or with some drain/refill or a combination -- your choice. You can start off buying half the amount of chlorine (i.e. 40 ppm FC worth instead of 80 ppm FC) and seeing what that does and where you end up. If there's still ammonia or CC left after that, then you can get more (I don't want you to end up wasting money buying more chlorine than you need).

You might check around at pool stores and hardware stores to see the price of chlorinating liquid (10% or 12.5%) as it might be more economical and certainly would be less weight to carry. Also, if any pool store reuses the bottles, then that saves on recycling (that's what I do with my pool store -- they reuse the bottles as I return the empties).

Richard

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Hi Richard,last night we put in 8 jugs of bleach. Today I tested the water, which is still clear, Ammonia .50, fc 1-2,ph 6.8, ta 100, cya 0. I say the fc is 1-2 because of the color. Listen I thought I had brought a Fas-dpd test kit, because that is what I asked for, but after reading someone elses problems I pulled the sticker off the top of the test kit and it just says dpd test kit. So I ordered the fas-dpd test kit and will be returning this one. Back to my pool. I believe I'm to add more bleach, but should I add only 4 jugs? And how long should I wait to test? I notice my ph is going down, should I do something about that now or wait? It's going to be a hot one today 90's, and I 'm worried about algea. Can I let the kids in the pool for the day and treat the pool at night?? Thanks again. I feel like I can see the light at the end of this long, long pool.-Debbie

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You never said the size of your pool so you should use The Pool Calculator to figure out dosing for chlorine. The ammonia is nearly gone -- the 0.5 ppm that is left will take about 5 ppm FC to get rid of. The pH may have dropped from the oxidation of the Combined Chlorine -- the oxidation of ammonia wouldn't have changed the pH (the pH goes up when chlorine is added and drops back down when the ammonia gets fully oxidized). So I suggest getting some 20 Mule Team Borax to raise the pH since that won't raise the TA as much as using a pH Up product (which is the same as Arm & Hammer Washing Soda).

Since you have no CYA in the water, I think the easiest way for you to get that raised while adding more chlorine is to buy some Dichlor powder/granules since for every 10 ppm FC that you add, it will also increase CYA by 9 ppm. You won't want to use too much -- cumulatively you'll want around 30-50 ppm FC but can just use this over time and build up the CYA over the next couple of weeks. After that, you'll want to switch to chlorinating liquid or unscented 6% bleach (e.g. Clorox Regular or off-brand Ultra).

By the way, in case you were concerned about where the ammonia went, it simply gets oxidized to nitrogen gas that escapes the water. The only thing left from it is some leftover salt from the chlorine that was used to oxidize it.

You're almost there!

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Richard,My pool size is 12x24, 9000 gallons. So I used the pool calc and added 1 jug of the bleach, my husband went out to get the borax, is that a liquid or powder? If powder, am I supposed to put in the whole thing if it is a 100 oz box? I don't know if I read that right?? He also went out to get the dichlor granules. We had trichloro tabs, but I guess that wouldn't do. So how long before the kids can go in after putting in the borax and dichlor?-Debbie

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Debbie,

It's a powder that comes in a 76-ounce (weight) box. Since your pH reading of 6.8 could be any pH lower than that, let's play it safe and add one box and see where you end up (if the pH were 6.8 and the TA were 100, then one box would raise the pH to about 7.2). If you still register a low pH, add another box. So your husband should probably get two boxes which should be enough unless the pH were below 6.6.

The Trichlor tabs would take too long to dissolve. The Dichlor is your fastest way to add both chlorine and CYA simultaneously via a powder/granules that dissolve fairly quickly.

As soon as you get the pH into a reasonable range between 7.2 and 7.8 and you get a measurable FC and CYA reading, your kids can use the pool. If you add enough Dichlor to get to 10 ppm FC, then by later that day the chlorine will drop and the CYA won't and the pool can be used -- say, at 5 ppm FC and 10 ppm CYA, for example. Though this is a higher chlorine level then you'll have longer term, it is a little less than that found in most indoor pools (5 ppm FC with 10 ppm CYA is equivalent to 1 ppm FC with no CYA). If you want to swim in lower chlorine levels, then add more Dichlor and wait longer for the chlorine to dissipate -- to 3 ppm FC with 20 ppm CYA for example. You'll have to estimate the CYA level based on how much Dichlor you've added -- roughly the amount of FC you added is equal to the amount of CYA (it's actually 10 ppm FC giving 9 ppm CYA).

As for chlorine usage going forward, you need to decide on your strategy. If you use Trichlor tabs, then the CYA will increase over time and you'll have to raise the FC level accordingly supplementing with another chlorine source or you'll have to use an algaecide (e.g. PolyQuat 60) or phosphate remover or you'll have to do partial drain/refill to dilute and lower the CYA level.

Richard

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Richard, Well we added a box of the Borax, which at first made my pool a little cloudy, then some of the dichlor gran, a 1 lb bag and a jug of bleach. We tested with the quick strips, because we're running out, fc 3,ph 7.2, ta 100 and stablizer low. We haven't had a reading on those test strips for the fc . Now to maintain. Can we just ad a jug of bleach a day?? Shock 1x a week? -Debbie

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I seem to be having the same problem. Slight yellow green tint to otherwise clear water. PH and Ak are fine, added some stabilizer and have a low reading of 20. No free chlorine, 3.0 reading from OTO test after lbs and lbs of shock over the last two weeks.

Pool Co. two different ones say water is fine, "add three bags of shock". Did it over and over. No free chlorine. Added more algaecide, let it run, added three lbs of shock, let it run and shut it off over night to try to kill and drag to the bottom the dead algae.

Next day a little better, still has a tint. No free chlorine. I have not had the water tested for ammonia as I just ran across that on this site. I was approaching a high cyanuric reading last summer, near 120 I think. There was none when we opened.

Out of curiosity I did your bucket test. It took four tsp of bleach to show up any free chlorine.

Advice Please???

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I seem to be having the same problem. Slight yellow green tint to otherwise clear water. PH and Ak are fine, added some stabilizer and have a low reading of 20. No free chlorine, 3.0 reading from OTO test after lbs and lbs of shock over the last two weeks.

Pool Co. two different ones say water is fine, "add three bags of shock". Did it over and over. No free chlorine. Added more algaecide, let it run, added three lbs of shock, let it run and shut it off over night to try to kill and drag to the bottom the dead algae.

Next day a little better, still has a tint. No free chlorine. I have not had the water tested for ammonia as I just ran across that on this site. I was approaching a high cyanuric reading last summer, near 120 I think. There was none when we opened.

Out of curiosity I did your bucket test. It took four tsp of bleach to show up any free chlorine.

Advice Please???

My water was always crystal clear, but we had no reading on fc and cya. I would go out and buy the ammonia test kit and test. When chemgeek/Richard replies, listen to him he knows his stuff. I feel so much better here, than going to the pool store. He was very helpful. Good Luck-debbie

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novice,

Congratulations! Do yourself a favor and get the better Taylor K-2006 or TF100 test kits instead of using test strips. Also, keep in mind that until your CYA builds up from the Dichlor usage, your chlorine will drop faster during the day, though not as fast as it would if you didn't have any CYA at all. Add the Dichlor until you've cumulatively added the equivalent of around 30 ppm or so, maybe more if you are in a very sunny area, but not more than 50 ppm worth. Switch to unstabilized chlorine after that.

The cloudiness when you added Borax probably means that your pool is pretty saturated with calcium carbonate. If you get the better test kit and measure your Calcium Hardness (CH) level along with other readings, then we can see if you need to do something else to balance your water better.

talkyfawn,

Go to a pet/fish/aquarium store and get an inexpensive ammonia test kit. You will need to add a Free Chlorine (FC) amount that is 10x the ammonia reading you get. This could be so high that it might be worth a drain/refill instead -- up to you -- but get the kit to see where you stand.

Richard

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Thank you,

I bought the ammonia test strips and I am getting a color that looks a little lighter than the 6 ppm. So I would say 5ppm. The next lighter is 3 and it is darker than that.

I have a 28,000 gal inground. I did the bucket test as described and did not get a fc reading until I added 4 tsp of bleach to the two gallons of pool water.

What should I do to get rid of this ammonia. I have never heard of this??

Thanks for the help.

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You can use The Pool Calculator to calculate how much chlorine you will need -- use chlorinating liquid or unscented 6% bleach (e.g. Clorox Regular or off-brand Ultra). You will need a cumulative amount of chlorine equivalent to 10 times the ammonia level, so say 50 ppm. You don't have to add it all at once and you should add it slowly over a return flow in the deep end with the pump running.

Get a good test kit (see my earlier links in this thread) and measure your Cyanuric Acid (CYA) level. If it's below 30 ppm, then you'll need to add some, either by pure CYA or by using stabilized chlorine for a while -- say Dichlor powder or Trichlor pucks/tabs.

In the future, try and winterize your pool by either keeping chlorine in it over the winter (if it doesn't freeze) or if you are in freezing climates where you shut off your pump, then shock your pool with chlorine, let it drop some, then add a large dose of PolyQuat 60 algaecide before closing the pool. Then, opening it as soon as you can in the spring before it gets warm and add chlorine to it.

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Thanks I will get some chlorine tomorrow. I had no problems last year when we opened the pool. I guess I didn't add enough shock and algaecide when we closed. I'll definitely pay more attention to that when we close it this year!

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OK, so I added 5 gal of 12.5% Liquid Clorine. How long should I wait to test the ammonia again. An Hour? Overnight? Should I let the filter run all night?

Thanks for your Help!!

Also can I add the CYA now or should I wait until the ammonia is gone?

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