Chlorine Lock ?

[mjsboone]

After 20 years of having a sparkling pool, we now have what the pool shop is calling a chlorine lock. Never heard of this before and after 25lbs of shock being dumped in out pool over the last 7 days, we really do not think the pool shop knows what to do. After reading about chlorine locks on this website, we went directly to the store and bought 6 gallons of bleach and put it in last night at dusk, waited an hour and tested (with the dreaded test strips that I am learning is absolutely the wrong way to test!) and all looked good. Tested again this morning at dawn and no chlorine, no free chlorine, and no stabilizer (no sure what that means either). The water is cloudy, is not green, but noticing algea on the string that holds thermometer and on ladder steps. Our pool is 23000 gallon, vinyl lined, in ground pool. AND, after fiddling with the filter, checking chlorine tabs over and over, I managed to break the auto chlorinator which was newly installed in April of this year. Now it is leaking all over the place when the filter comes on. Ugh!

[PoolDoc]

we now have what the pool shop is calling a chlorine lock . . . we really do not think the pool shop knows what to do.

You nailed it!

"Chlorine lock" is a term like "dermatitis".

(You tell your doctor, "Doctor, I have red and itchy skin!". And the doctor says, "Ahh, my young (or old) friend, you have dermatitis". That sounds impressive, till you find out "dermatitis" basically means reddened or irritated skin!)

When pool stores say, "you have the dreaded CHLORINE LOCK", what it means is, "We don't know what's going on with your chlorine, but we've found a better way to say that!".

That said, if 6 gallons of bleach disappeared overnight, you DO have a problem! And I'll tell you right away, I don't know why.

That said, I can tell you that similar problems are *usually* caused EITHER by
(a) emerging algae -- but usually not overnight, OR
(b) by something you put in the pool.

So do all these things:

1. Tell us what you most recent test results are, including pH
2. Keep adding 2 gallons of PLAIN 8% bleach EVERY night till this is resolved. (Doing so will GREATLY reduce the risk of you developing a swamp in your back yard!)
3. Give us a list of EVERYTHING you added to your pool in the 2 weeks prior to developing a problem. Exact maker & product name, please.
4. Order a real test kit: http://pool9.net/tk/
5. Run your pump 24/7.

I'm confident we *can* figure it out!

[mjsboone]

I cannot begin to remember everything that has gone into the pool prior to this chlorine lock. My husband feels this has been coming on for at least six months beginning with an abundance of leaves that blew into the pool from a neighbor's "stockpile" of leaves from his back 40. It seems we have had trouble ever since with staining, algea, and now this cloudiness that will not go away. Other than regularly adding chlorine 3" tabs to the auto-clorinator, some algicide, some ph down, and 2 cases of plain Bioguard shock, that's it. I cannot recall the amounts of anything except most recent mega dose of shock. Oh...the 6 gallons of bleach last night. We will get a test kit today from the dreaded Walmart so as not to wait. I will begin adding 2 gallons of bleach per night beginning tonight. Will test asap with new test kit and post results.

[PoolDoc]

Get the OTO / phenol red drops kit, preferably the HTH 6-way (made by Taylor), but if not available, get a cheapo 2 bottle model. OTO is not very accurate but it's VERY reliable, can covers the entire range from 0 - 60 ppm.

Stop using BioGuard products -- they are among the worst about adding mystery ingredients that will screw up your pool. A BIG part of our approach here is to use ONLY known chemicals, and ONLY when there's a clear and specific purpose for doing so. We recommend the "add some and see if it helps" approach very, very rarely.

That's why we steer people to no-name commodity products that are simple, undiluted and unblended.

[mjsboone]

Our pool is looking better this morning. More clear. Attempts to find a test kit failed yesterday. Pool supplies seem in short supply in South Carolina in the dead of summer. Can't quite understand that, but I will persevere today in the hope of finding-otherwise will order from Amazon. I tested the water this morning with the test strips :( and the results were: chlorine 0, free chlorine 0, and ph 7.4. If I understand your directions clearly, I should continue to add 2 gallons of bleach every night until the testing the next morning show that the water is holding the chlorine throughout the night. Is this correct? I hope to have the good kind of test kit today. Wish me luck on my quest! Thank you for your guidance!

[Watermom]

If you are registering 0 chlorine this morning, you don't want to wait until evening to add bleach. Go ahead and add it now if you don't want your pool to turn green!

A pool store should have an OTO kit. Just don't let them talk you into buying anything else while you are there. They will try! But, even after you do get a cheap OTO kit, you still should order a K2006. That kit will not be available locally and you will have to order it. (Link in PoolDoc's post above.) If your pool store happens to have a K2005 don't buy it. Not the same thing and not what you want.

[mjsboone]

Is all this bleach hurting my liner? Also, if I am seeing the pool look clearer this morning, it does not mean that things are improving? I will add the 2 gallons of bleach now although I am cringing. I have got to hang in there and get this problem solved! Thanks for your guidance-again.

[Watermom]

If you have no chlorine in the pool, the pool will turn green. Plain and simple. And, it doesn't take long before algae starts.

Bleach is 8.25% sodium hypochlorite. Pool stores also sell liquid chlorine. It is either 10 or 12.5% sodium hypochlorite. The same stuff only more concentrated. People do not hesitate to add pool store chlorine but when they hear the word 'bleach,' they get scared. If you wouldn't be afraid to add pool store chlorine, then you shouldn't be afraid to add bleach. (In all the years I have had a pool, I have never used anything but bleach for my source of chlorine.)

Those gallons of bleach aren't actually gallons but rather they are 121-oz jugs. In a 23K pool, adding two of those jugs is only going to take your chlorine level up to a little less than 7ppm which is not all that high. Nothing to worry about at all.

Test the water again this evening and repost with the numbers. It is likely that you will need to add more bleach this evening as well. And, go ahead and order a good kit ASAP using the link Ben gave you so you'll get it as soon as possible.

[PoolDoc]

It's very unlikely that you'll be able to buy a K2006 locally. I've encountered exactly one case of a pool store stocking that kit . . . and hundreds that don't. It's hard for pool stores to get excited about a test kit that is, fundamentally, designed to put them out of business.

Please go ahead and order one. You're going to end up in real trouble without it.

[mjsboone]

Good evening! Just tested the pool with a new basic testing kit (have to order the "good" one). And here are my numbers after putting in 2 gallons bleach last night and 2 two more this morning. Chlorine is almost non existent at the 0.6-1.2 and ph is 7.6. We added 2 more gallons after the water was tested. I will test again in the morning to see where it's at. Any other suggestions at this point?

[Watermom]

Test it again an hour after you added the bleach and report the chlorine reading. Don't need to test pH again.

[mjsboone]

Test results one hour after adding 2 gallons bleach: chlorine 1.5-3

[PoolDoc]

2. Keep adding 2 gallons of PLAIN 8% bleach EVERY night till this is resolved. (Doing so will GREATLY reduce the risk of you developing a swamp in your back yard!)

Unless your water looks bad, I wouldn't worry about adding in the AM. I'm guessing your stabilizer is low, but we won't know till you have a kit.

What would be interesting is to add 2 (or 4) gallons at night, and then test in the AM BEFORE the sun starts hitting the pool. Again, once you have the K2006, we'll be able to tell more.

[mjsboone]

It will be a week before we are able to get the more extensive testing kit. My question now is, do we keep adding the bleach every night and for how long? Would this be the routine from this point forward or at some point do you just add the bleach on a maintainance schedule? The water is clearing nicely, but we see slight algea by the ladder and a little in the shaded corner of the pool.

[CarlD]

Just keep doing what you are doing. WM and PD know best. I'm surprised there isn't a WalMart near you with the HTH 6-way drop test kit. That's the best thing short of the Taylor K-2006.

WaterMom uses bleach in her pool. I use Liquid Chlorine in mine. Same thing, but there is ONE store that sells LC in 5 gallon carboys that turns it over so fast their stuff tests out at 14% though they nominally sell it as 12.5%. What's the difference between that and 8.25% chlorine bleach? Only in the amount of chlorine added to your pool.

If your pool was 10,000 gallons, one jug (121 ounces) of 8.25% bleach will add 7.8ppm of chlorine. But if you add 1 gallon of 12.5% LC, it will add 12.5ppm of chlorine. (you need twice as much of each to get the same addition of chlorine in a 20,000 gallon pool). That's the only difference between bleach and LC.

As for bleaching your liner, you need to really raise your chlorine level very high before you do that--and EVERY kind of chlorine can do it regardless of the source.
Generally, if you "shock" your pool to the recommended level based on your stabilizer (aka CYA) level, you have NO fear of bleaching your liner. However, over the years, the sun WILL fade it anyway. Personally, it's not a big concern of mine as long as it's not weakened. But that's me.

[mjsboone]

Just found out that Ace Hardware carries HTH 6-way drop test kit. I've been everywhere today looking for ANY test kit and ended up at the pool shop buying the very basic kit to get by. I fail to understand why the stores in South Carolina, where the pool season begins in April and ends in October, do not stock pool supplies once you hit July. It is slim picking! Off to Ace Hardware tomorow. Continued thanks to all for the advice!

[PoolDoc]

Nobody wants to carry expensive inventory all winter.

Keep up with the bleach till you have test results from the K2006. The 6-way will help -- you can test stabilizer -- but in your particular situation, accurate measurement of FC vs CC is needed, and only the K2006 will give you that.

But, the 6-way is compatible and useful, so don't regret having both. Do post CYA results from the 6-way -- watch the Taylor video for the K2006 CYA test; it's almost the same as the 6-way.

[Watermom]

Adding two jugs this evening should have added just under 7ppm. You report only 1.5-3ppm only an hour after testing which means your chlorine is being eaten up pretty quickly. If it were my pool, and especially since there is algae, I'd add more tonight and probably more than 2 jug doses. Ben, do you not agree with this?

[mjsboone]

Well, this morning brings zip zero chlorine. I want to say that I could see a tinge of yellow in the test bottle, but not enough to register on the lowest level of the vial. Since I don't have the fancy test kit, I used the test strip to check stabilizer and it indicated it was in the "ok" range. My stockpile of bleach is now gone so off to the store again. The water is clear, thank goodness. Nothing worse than looking out your windows and seeing a cloudy pool or green pool for that matter. Now I do realize that I need a better kit, but will not have that for a while. What will actually resolve this chlorine lock and what kind of time frames am I looking at? Thanks everyone.

[BigDave]

I haven't heard of the hth 6-way drops kit anywhere but wall mart; it's not on ACE's website.

The test strips for CYA are useless - they just don't work. No one here can advise you regarding your pool without accurate measurements. I'm sorry.

The only thing you can really do without a K-2006 is keep dumping bleach in the pool and hope it stays clear - maybe take OTO reading and dose bleach multiple times a day.

Please remember: chlorine lock doesn't exist - it's just something you were told by someone afraid to say "I don't know".

[mjsboone]

Thanks. Now I am really discouraged...

[BigDave]

I'm sorry. :( I didn't intend to discourage you. What we know is that you have chlorine demand but we don't know why. The only thing to do is pour bleach in it - but enough bleach - too little is usually just wasted.

[mjsboone]

Please tell me how much bleach and for how long. So far I have put in 12 big bottles of bleach since Saturday. I'm not a chemist, just trying to get the pool chemically correct so it is clear and healthy. I'm sorry I do not have the very expensive test kit but it is what it is and I will continue to try to figure this out. I have had a pool all of my life and never have I had this difficulty getting the water balanced using all the typical pool store products with secretive names. Now, in the past month, none of their products have worked and their directions of add this first, wait 15 minutes, add this second, divide this in thirds, ect...have worn me out and my pocketbook out! Adding the bleach has improved the look of my pool, but I still want to know if this is going to be an every night event for the duration or will the water eventually hold the chlorine throughout the night and a maintainance schedule will keep it where it needs to be. Can anyone answer that question for me?

[Watermom]

Eventually, the chlorine demand will go away but it takes time.

No way to know for sure but sometimes what happens to pools is that the CYA biodegrades over the winter and leaves behind a bunch of byproducts such as ammonia that cause a huge chlorine demand the following season when the pool is opened. I have a feeling that is what is happening in your pool.

The only way to get rid of the byproducts and thus the chlorine demand is to add lots of bleach. It will probably get a little expensive to buy all the bleach but there is no other way around it other than a lot of chlorine. Since you have no chlorine in there now, you must add some or you will not only have a pool with high chlorine demand, you will also have a green pool to go with it!

Each of the 121-oz jugs of bleach will add about 3.5ppm of chlorine. Go ahead and add 4 jugs this morning. A couple of hours later, test your chlorine and see what you show. You will have to use this chart to make a guess of what the reading is:> http://pool9.net/oto-chart/

This evening, test again and see where you are. And, then again, add enough bleach to get back up to around 15ish. It may take several days of keeping the chlorine high before the chlorine holds but eventually it will.

If you can get the K2006 kit, it will make this a whole lot easier.

[Big Splash]

Please tell me how much bleach and for how long. So far I have put in 12 big bottles of bleach since Saturday. I'm not a chemist, just trying to get the pool chemically correct so it is clear and healthy. I'm sorry I do not have the very expensive test kit but it is what it is and I will continue to try to figure this out. I have had a pool all of my life and never have I had this difficulty getting the water balanced using all the typical pool store products with secretive names. Now, in the past month, none of their products have worked and their directions of add this first, wait 15 minutes, add this second, divide this in thirds, ect...have worn me out and my pocketbook out! Adding the bleach has improved the look of my pool, but I still want to know if this is going to be an every night event for the duration or will the water eventually hold the chlorine throughout the night and a maintainance schedule will keep it where it needs to be. Can anyone answer that question for me?

Boone, I think you'll find it is very difficult for the experts here to offer advise without you reporting testing results from the recommended test kit.

You've done well over the years, but you've now hit a wall that is created by using those pool store products blindly. I'm certain everyone here wants to help you. But without good test data being reported by you, nobody wants to end up making a recommendation that could make things worse.

Make the investment if you can in the Taylor kit and you'll find more money in your pocket in the end.

Best,
Splash

[mjsboone]

Thanks Watermom and Big Splash. I appreciate your constructive responses. :) The more I read, the more I understand about the process. Off to buy bleach by the trunkful.

Jane

[PoolDoc]

Well, this morning brings zip zero chlorine. I want to say that I could see a tinge of yellow in the test bottle, but not enough to register on the lowest level of the vial.

Overnight chlorine loss almost certainly indicates that there is something in the water that the chlorine is oxidizing. The only solution to this is to chlorinate till it's gone OR to drain and refill. (Remember, most inground pools cannot be drained safely without special precautions). You can do the bucket demand test to see how much chlorine it's likely to require: http://pool9.net/bucket-demand/

Unfortunately, we can't tell you WHAT is in the water. We'd know a little more, if you had the K2006. I can tell you that your problem originated in one of two ways: EITHER, it's something the pool store has been selling you -- and yes, stores sell MANY worse-than-useless products -- OR it's partially degraded stabilizer (cyanuric acid), resulting from a period of biofilm (bacterial slime) activity in your pool.

[sabres07]

No disrespect meant here, but really the first thing you need to do is buy the Taylor test kit. Without reliable and accurate numbers, the advice you will get here is more "general" in nature which translates to more cost and time spent clearing up the problem. There is a reason why every first answer to each thread in this forum starts with "what are your numbers? If you don't know, get a good test kit".

[Watermom]

No disrespect meant here, but really the first thing you need to do is buy the Taylor test kit. Without reliable and accurate numbers, the advice you will get here is more "general" in nature which translates to more cost and time spent clearing up the problem. There is a reason why every first answer to each thread in this forum starts with "what are your numbers? If you don't know, get a good test kit".

What he said! ;)

[sabres07]

As a point of referrence, I was told I had 'chlorine lock' a few years ago by my pool store after having the same problem you are having now. No matter how much chlorine I added it would get eaten up almost immediately. So I googled chlorine lock and found this site....I have not set foot in a pool store since then and my pool has been crystal clear, too, since I have been following the BBB method. By the way, it took something like 30-35 gallons of 12% chlorine to kill whatever was causing my chlorine demand. We eventually figured my problem stemmed from a degredation of CYA over the winter which created ammonia as a waste product. Vast amounts of chlorine are needed to rid the ammonia.

[JimK]

As a point of referrence, I was told I had 'chlorine lock' a few years ago by my pool store after having the same problem you are having now. No matter how much chlorine I added it would get eaten up almost immediately. So I googled chlorine lock and found this site....I have not set foot in a pool store since then and my pool has been crystal clear, too, since I have been following the BBB method. By the way, it took something like 30-35 gallons of 12% chlorine to kill whatever was causing my chlorine demand. We eventually figured my problem stemmed from a degredation of CYA over the winter which created ammonia as a waste product. Vast amounts of chlorine are needed to rid the ammonia.

I also had to deal with the effects of CYA degradation this spring. I estimate I lost about 40ppm of CYA. It took about 26 jugs of 8% bleach before CL levels stabilized. It's been smooth sailing from there. :)

[mjsboone]

Today I received the official K 2006 test kit that I ordered. After reading the directions, I realized that they are quite detailed! Can anyone offer advice in plain English to get me through this testing procedure?

I've been keeping the pool looking pretty good by the addition of bleach but it's teetering on the edge of algae hell-I can just tell. I am hoping to get the numbers I need to get the guidance I need to settle my pool problem once and for all. Thanks all!

Jane

[Big Splash]

Watch these videos in this thread

Taylor K2006 Videos on YouTube
http://www.poolforum.com/pf2/showthread.php/17157-Taylor-K2006-Videos-on-YouTube

[BigDave]

Watch the videos and ignore the booklet and the wheel, they are unnecessarily confusing.

[robbym70]

nix the booklet and watch the vids. Also...the instructions inside the box on the inside label are pretty easy to follow.

With the test tube thingy you have three levels marked on the side. Use the smallest level it will save you in the long run and the measurement is just as good. Fill the tube with water up to the first line. Add two small spoonfuls of the white powder than swirl it around. Then add the titrating agent drop by drop slowly swirling it around after each drop. Multiply the number of drops by .5 and that is your FC measurement. 8 drops of titrating agent = FC of 4 etc etc.

CYA level is key. It will tell you how much chlorine you need to add for both shocking your pool and simply maintaining the levels. Look in Watermom's siggy for links to the "Best Guess Chart" and read the text that goes along with it. This info is key to utilizing the BBB method successfully.

[BigDave]

...the instructions inside the box on the inside label are pretty easy to follow. True that!



...Use the smallest level it will save you in the long run and the measurement is just as good...Also true, most of us use the 10ml sample to test chlorine. In fact if one dipper of powder turns the water pink - that's all you need.

[mjsboone]

Okay you guys...I freaked out a little when I opened that test kit box. I'm just a novice. The videos helped. :)

I hope I did the testing correctly. Here goes!

FC 6.8
CC 4.4
PH 7.4
TA 120
CALCIUM HARDNESS 130
CYA It was less than the 100 mark (was not sure what number to put)

[PoolDoc]

FC 6.8
Ok, if rather low, given your CYA level.


CC 4.4
Should be less than 0.5 ppm. This is WAY too high, and indicates that there is STILL stuff needing oxidation.


PH 7.4
TA 120
CH 130
All fine. It wouldn't hurt to use borax to raise your pH, however. The by-products of the oxidation process tend to be 'nicer' at a higher pH level.


CYA It was less than the 100 mark (was not sure what number to put)
This indicates that your CYA level is MORE than 100 ppm. That's consistent with the theory that you had high CYA, that was partially metabolized by bacteria to form ammonia.

You'll eventually need to retest, using a 50:50 dilution of pool water with DISTILLED water, and multiply the result x2. You must use DISTILLED water and not "spring" water or any of the other variants: http://www.walmart.com/ip/10315382

[mjsboone]

Thank you for looking at my numbers. What exactly should I do now. I've been adding bleach everyday until I got the test kit and the numbers needed to determine the problem. Will I be adding bleach everyday from now on or should I be doing something else? I guess I remain a little confused about the next step.

[Big Splash]

If it were me, I'd retest the cya using the diluting method 1st. You may need to drain. You'll just be wasting bleach if you need to drain. Good testing aways gives you good answers about what to do next.

[PoolDoc]

Yes, we need to verify that your CYA is really as high as it appears, before we can really proceed. Watch the CYA video again.

And, take a look at these Taylor images:

https://www.taylortechnologies.com/managed_content_44_files/image001.jpg

https://www.taylortechnologies.com/managed_content_44_files/image002.jpg

https://www.taylortechnologies.com/managed_content_44_files/image003.jpg

[mjsboone]

I tested CYA again and maybe I did do something wrong the first time. I really watched until I was SURE I didn't see the black dot and now it registers about 80. Does that help? Hang in there with me-please!

Jane

[Big Splash]

80 is pretty high but workable. This late in the season, draining might not be worth it. Its up to you. Check the best guess chart for the amount of bleach youll need at 80 cya (24 FC I think) to stay at shock levels.

[mjsboone]

I have looked at that chart and have no idea what it means. I don't mean to sound stupid here, but am I missing something? Where does the chart indicate how much I need to add? Is there anyone who can explain this to me?

[Watermom]

So, if you did the dilution and the test read 80, that means your CYA is 160 since you have to multiply the result by 2.

With a CYA of 160, you need to keep your chlorine levels between 8-15 ALL the time. If you dip lower than 8, you risk an algae bloom. And, when you need to shock the pool, your shock level will be 25ppm.

What is the volume of your pool?

[mjsboone]

23000 gallons

[Big Splash]

Did you test with a 50/50 diluted sample or no?

[Watermom]

So, each evening, when you test your chlorine, you'll want to add enough bleach to take the chlorine level up to 25ppm. In case you have forgotten from a post earlier in this thread, in your pool, each of the 121-oz jugs of 8.25% bleach will add about 3.5ppm of chlorine. Use that as a reference to figure out how much bleach to add each evening to get back to 25ppm. You'll want to continue keeping the chlorine level at 25ppm by using bleach until you meet 3 criteria:

1) You lose no more than 1ppm of FC from sundown to within one hour of sunrise the next morning.
2) You have no higher than 0.5ppm of CC
3) Your water is clear

At that point, keep the chlorine at 25ppm for one additional day and then you can let it drift down and keep it between 8-15 ALL the time. I would not advise using any more stabilized forms of chlorine in your pool like trichlor tabs or dichlor powder as they will both make your CYA continue to climb and yours is already really high.

Also, remember that when you test pH, you will get an invalid result if your chlorine is over 10ppm with a Taylor kit. (Over 5ppm with other kits.) So, dilute your sample -- half pool water and half distilled water and run the pH test with that mixture if your chlorine level is over 10ppm.

When you do the chlorine test, use the 10mL sample instead of the 25mL one and it will make your reagents last longer. You'll multiply the number of drops by 0.5 instead of 0.2. Also, if one scoop of the powder turns the water pink when you do the FC test, you don't need to add the second one. That, too, will save on your reagents.

Hope this helps.

[Watermom]

One more thing. Please make a signature. In it, please give the type of pool, volume, type and size of pump and filter, city water or well water and the fact that you have a K2006. That makes it easier for us to help without having to constantly scroll back through this long thread. You can make a signature by clicking on the tab in my signature below. Thanks!

[mjsboone]

Thank you Watermom! With the help of my son, we finally figured out what I have to do... add 5 jugs of bleach to get to 25 ppm and enough to keep it at that level every night until the 3 criteria are met. Might need some help once I get to that point.