Frustrated on trying to break Chlorine Lock

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Mark Albright

0
Aug 4, 2015
5
New Baltimore, MI
I have a 30,000 gallon, chlorine pool. Last fall my CYA was over a 100 when I winterized it for the winter. This summer when I uncovered it I drained 15,000 gallons of water out of my pool and refilled it with fresh water from our city via my garden hose. It took 30 hours.

When I tested the water with my Color Pro 7 test kit with new reagents (I use this because I am color blind) I got the following readings:

Free Chlorine - 2.82
Total Chlorine - 4.75
PH - 7.3
Total Alkalinity - 137
Total Hardness - 184
CYA - 11

I took a sample of my water to the local pool store and they confirmed I had a chlorine lock, high phosphates, low total hardness and CYA. They wanted me to address the high phosphates first. They had me do the following:

But natural chemistry phosphate remover and had it to the skimmer over 2 doses of 50 oz. each and run the pump for 48 hours. I did that and the phosphates cam down to 1000. I did it again and the phosphates went back up.

They ten told me to not worry about that right now and said we would address the chlorine lock. They had me do the following:

Put 4 gallons of liquid Chlorine and 3 lbs of non chlorine shock and run filter for 48 hours. I returned to store and was told I still had chlorine lock. They then told me to put 2 gallons of liquid chlorine in the first evening and add a gallon of chlorine in each evening for the next 7 days. After that I still had chlorine lock.

I then decided to drain a portion of the pool again. I took 11,000 more gallons out of the pool and replaced it again with fresh water from our city via my garden hose. It took another 20 some hours.

When I tested the water with my Color Pro 7 test kit with the new reagents again I got the following readings:

Free Chlorine - 0.39
Total Chlorine - 4.59
PH - 7.2
Total Alkalinity - 99
Total Hardness - 348
CYA - 17

I first added 6 lbs of alkalinity plus to my pool to bring up the alkalinity. I waited 4 hours and added 6 lbs of super shock to my pool ad let it run over night. Listed below are the reading I got today from my color pro 7 test kit.

Free Chlorine - 1.33
Total Chlorine - 4.59
PH - 7.3
Total Alkalinity - 116
Total Hardness - 358
CYA - 19

I also had my wife read new test strips I have from HACH they are Aquachek 7. They confirm i still have a chlorine lock because my FC is registering close to 0, my TC is between 3 and 5, CYA is low, but PH, TA and TH seem okay.

I have no faith in the pool stores. Another pool company stopped by today and told me to keep shocking it with 6lbs of super shock each night until I break the chlorine lock.

Needless to say I have wasted a lot of money and time on this pool. I am hoping someone on your site can give me some good advice that will break my chlorine lock and let us enjoy our pool.
 
Hi Mark! There's no such thing as chlorine lock. What is the condition of your pool - is cloudy? Green? I'm sure some other experts here will provide some great advice but I recommend reading up on pool school here and stop going to the pool store. They sold you a bunch of stuff you didn't need. Keep a positive attitude and these folks here will help you get the pool squared away. :)
 
Your CC's are probably high because of that non-chlorine shock the pool store sold you. It can show up on tests as high CC's. If your pool is green or cloudy, you should really do a SLAM. It's our version of shocking the pool, but it's not a one time event. You raise your FC to a shock level based on your CYA and keep it there by testing and redosing several times a day until the pool is crystal clear, your CC's are .5 or less and you pass an overnight chlorine loss test (OCLT).

I'm not familiar with your test kit, but just from your two cya tests you did, I'm questioning the results. If you drained a second time and after the refill, your CYA was higher, that doesn't make sense. It should have gone down like the first time. I would get one of the two recommended kits. Either the TF-100 or the Taylor K2006C. They are the only ones with the coveted FAS-DPD chlorine test that allows you to test for high levels of chlorine accurately (up to 50 PPM). You need to know what your CYA really is so you know what level you need for your FC during your SLAM.
 
My pool is crystal clear, no cloudiness. I have 4 different testers, a Guardex and Taylor which rely on colors and I have a hard time with because of my color blindness, the Aquachek 7 made by Hach and the Color Pro 7 made by LaMotte which offers digital readouts. This one is perfect for a person with color blindness and gets great reviews as long as you keep the reagents up to date. I just had the pool store down the street test my pool water again and they confirmed I have chlorine lock and low CYA.

- - - Updated - - -

My pool is crystal clear, no cloudiness. I just had my pool water again tested at the pool store near me and they confirmed I have chlorine lock ( no FC chlorine and a lot of TC) and my CYA is low.
 
I'll stay out of the whole chemical aspect of this conversation, and just make a suggestion of something to try.

Based on my experience here and with my pool, I'm confident it two things. Pool stores, and pool maintenance companies can steer your wrong. Ignoring both and following only TFP advice and teachings can solve for virtually any pool chemistry problem, certainly the ones you are experiencing.

What you have been doing is not working for you. Neither are the testing methods you are using. If you want to solve your pool issues, maybe it's time to embrace something other than what you've been doing. If it doesn't work, you can always go right back to what you've been doing, yes? Nothing lost.

Can your wife help you with the colors? Get her involved. Get one of the two recommended test kits. Stop using any others. Don't question that, or compromise that advice. Just do it. Stop going to the pool store. Stop listening to pool guys.

Give TFP a month. Don't deviate, at all, from their instructions. Don't inject your own logic, or that of any other source. Give TFP a real shot. If you do all that, faithfully, your pool will very likely be amazing, and trouble free. It has happened for 10s of thousands of other people. This is the real deal. What have you got to lose?
 
:goodpost:

Our methods are incompatible with Pool Stores such as yours that want to sell you an elixer every time to you go in. Most of us maintain our pool all season with nothing but some bleach and muriatic acid at a cost of $20 or less per month. You don't need phosphate reducer, non-chlorine shock, yellow out, or anything else to address fictitious and unscientific "problems" like "chlorine lock".

You need to SLAM to get rid of those CCs, and then some filtering to get rid of whatever appears when you SLAM. Just because the pool looks somewhat clear doesn't mean it is actually sanitary and clean.

SLAM: SLAM Process
 
Your problem is not "Chlorine Lock."

The high Combined Chloramines is probably just interference from all the non-chlorine shock. Or it really is CC, created from chlorine and Ammonia. CYA can break down into ammonia, and it takes about ten times as much chlorine to neutralize it. If it were Ammonia, at opening, if you read almost 5 ppm CC, that means it would take about 50 FC to neutralize it. That's a heckuva lot of chlorine in a 30,000 gallon pool. About fifteen gallons of high-strength pool shock by my estimation.

But let's address some of the other things going on. Phosphates. Who cares? If you have adequate chlorine to sanitize the pool, you have adequate chlorine to kill algae, so there's no reason at all to worry about Phosphates. Unless you're out to make a few bucks selling miracle snake oils to unwary pool owners.... How did the Phosphates go UP? :scratch: How about.... poor testing?

It would be nice if you had a better test kit. But I'll accept those readings before I'd accept any pool store test or test strip results.

But now you want a course of action.
1) throw away test strips
2) Vow to never go to a pool store for testing again.
3) Load up on plain bleach - pool shock - liquid pool chlorine - whatever name you want to call Sodium Hypochlorite. Nothing with scents, antisplash additives, or fabric protectors.
4) Take initial readings of FC and TC. Remember the equation TC-FC = CC
5) Add 3 jugs of 10% bleach or equivalent. You want to take FC to 10. Brush a little to get it mixed well. Retest in 10 minutes. If FC is almost gone and TC climbed, it's ammonia. Just keep adding bleach to get to 10 FC and retest every ten minutes until the FC stays above 5 and the CC starts dropping.
6) Report back for the next steps.
 
I have the Lamotte ColorQ Pro 7 test kit as well as the TF-100 kit and I have noticed that the Lamotte kit shows a much lower FC and TC level than the TF-100 kit at levels over 5 ppm, and also can't give results at higher FC levels needed to maintain a proper SLAM. The PH usually reads about 0.2 lower than the TF-100, the ALK is close (within 10 ppm) and the CH is always low...sometimes half of what the TF-100 reads depending on how old the CH2 reagent is. The CYA reading is usually pretty accurate.

I am also color blind, but I can still run accurate tests on the TF-100 since I can see the color changes, even if they are not true colors they way other people see them. It is the change that matters and when you add another drop and nothing changes, subtract that drop for your measurement. I'd recommend getting the TF-100 kit with the speed stir and comparing your Lamotte results with the TF-100. That way, when you are in normal maintenance mode, you can use the Lamotte kit to identify any drift in readings, then use the TF-100 to obtain your "real" measurement for making adjustments to your pool chemistry as needed.

Follow the SLAM procedure using liquid chlorine to address the FC problems and you should soon be good to go.

Stay out of the pool store...your wallet and pool with thank you later.
 

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Mark Albright said:
Thanks for the advice. I made sure the PH was at 7.2 and then I shocked the pool with 6 lbs of super shock in the evening and adjusted the CYA to 30 and everything is good now.
Click to expand...

Unless you’ve tested with a proper kit and SLAM the pool just throwing 6 lbs of super shock is not going to solve your problems.

If you don’t manage your CYA level by either using liquid chlorine (aka bleach) or drain and fill when using chlorine pucks your CYA is going to creep back up to 100+ and this cycle will continue. If you use trichlor pucks they add a certain amount of cya and chlorine at the same time. This is the reason you had a high cya at the beginning of the season.
 
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