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.