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Thread: Way too high chlorine level and staying that way for weeks

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    Way too high chlorine level and staying that way for weeks

    I've been a pool owner for 20 years and do my own maintenance. I've never seen this before. All the other water chemistry is normal except the chlorine. It's off the chart on my tester.

    I used the floating chlorinator with 3" tablets. I've kept this out of the pool for 5 weeks hoping that the chlorine level will lower itself. Nope. Still high. It still must be still effective because there is no algae.

    Any idea? Thanks in advance.

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    Mod Squad tim5055's Avatar
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    Re: Way too high chlorine level and staying that way for weeks

    Welcome to the TFP pool!

    My first question is, what are you using to test the chlorine level?

    Just because there is no visible algae does not guarantee that the pool is sanitary.
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    Re: Way too high chlorine level and staying that way for weeks

    Welcome to the forum

    Chlorine cannot continually stay in a pool. It is consumed by UV from the sun and organics in your pool.

    So, to get to the bottom of the issure we need a full set of current test results to get started. Can you post those?
    Dave S.
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    Re: Way too high chlorine level and staying that way for weeks

    Hello Tim5055. (please don't laugh) I am using the Leslie's Deluxe Poolcare OTO Test Kit. In particular to the chlorine level, I add 5 drops into a colored container (yellow spectrum). It typically in the mild 2 - 3 range (as in past 11 years). The current reading is off the chart. It's super thick yellow. I am guessing like an 8 or 10.

    - - - Updated - - -

    I will post a full test by taking the water to the pool store on Monday. But here is the reading from my home test kit:

    Total Chlorine Level = 10
    pH Test = 8.2
    Total Alkalinity = 90 ppm

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    Mod Squad kimkats's Avatar
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    Re: Way too high chlorine level and staying that way for weeks

    The biggest draw back on that test is it only goes up to 5. It also does not show you a true picture of the CC (combined chlorine). That is the FC (Free chlorine-the good stuff that kills algae) and the CC (combined chlorine-the bad stuff showing you have something growing in your pool). The FC+CC=TC (Total chlorine). All the chlorine tests shows is the TC

    You are also missing a couple of very important tests such as the CYA (stabilizer) and CH (calcium hardness). Both of which cna really impact your pool care if they are too low or high.

    Here is a link to show you the kits we like:

    Pool School - Test Kits Compared

    The pool store test will not do you much good. Most of them don't use proper testing procedures such as not cleaning between tests, not calibrating the testing machine, etc. Do yourself a favor and get a proper test kit.

    Kim
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    Re: Way too high chlorine level and staying that way for weeks

    Quote Originally Posted by cutaway View Post
    Hello Tim5055. (please don't laugh) I am using the Leslie's Deluxe Poolcare OTO Test Kit. In particular to the chlorine level, I add 5 drops into a colored container (yellow spectrum). It typically in the mild 2 - 3 range (as in past 11 years). The current reading is off the chart. It's super thick yellow. I am guessing like an 8 or 10.

    I will post a full test by taking the water to the pool store on Monday. But here is the reading from my home test kit:

    Total Chlorine Level = 10
    pH Test = 8.2
    Total Alkalinity = 90 ppm
    Could the test kit be old/expired? That would be my first guess. I hope you understand that it is scientifically impossible for chlorine to stay in the pool for as long as you describe. The OTO test has a limit of 5 for chlorine (the 10 is for Bromine, using the same tube/scale).

    But, with that being said not much credence is given to pool store testing around here. We find that many times pool store employees primary goal is to sell stuff, not necessarily get your pool in perfect condition. As to whether that is because of improper training, lack of knowledge or just to sell stuff I will leave up to you. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. Plus, the results of their "testing" is used to convince you that you need to buy things. Why do you think that testing is free?

    But, what can you do?? We base our pool care system on accurate testing and only adding what the pool needs, when it needs it. To do that you need your own accurate test kit. Order a TF100 test kit

    Please don't go back to the pool store for a test kit. To effectively practice the TFPC methods, the FAS/DPD chlorine test is essential. The TF100 test kit has this test while very few other kits do. The kits sold at the pool store generally won't won't cut it, but be careful pool store employees are known to say “it's the same thing”. Generally it's not!


    The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want. Even then it is a little short on the reagent & powder for the FAS/DPD test.

    What we teach is vastly different from what both pool stores and long time pool owners like yourself are used to.

    Unfortunately the pool industry has evolved into sales by scare tactics, misdirection, misinformation and marketing hype. Go in to the store and tell them your TA is low and they are going to sell you baking soda in a fancy package at four times the cost of WalMart. Do they have a right to make a profit, yes - but lets be reasonable. Heck, even their definition of "low" can many times put you on a pH roller coaster that's hard to get off of. Is that lack of knowledge or a sales technique to sell you more chemicals to control your pH????

    What do we propose? As i said above, we base our pool care system on accurate testing and only adding what the pool needs, when it needs it. Which leads to:

    TFPC tenet - Never put chemistry in your pool when you do not know the outcome

    For almost everything the pool store sells, there is a generic "twin" that you can get at your grocery store or big box store. Alkalinity low? you can go to the pool store and buy Alkalinity Up in a fancy bottle or you can stop by HEB and pick up baking soda.

    So, to control your pool you need to know what is going on. many folks have a Saturday morning ritual, dip a bottle of water out of the pool and take it to the pool store (they give you the bottle for free). They test it and sell you what they say you need to "fix" what ails your pool. But, you will find not much credence is given to pool store testing around here. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. Plus, the results of their "testing" is used to convince you that you need to buy things. Why do you think that testing is free?
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    Re: Way too high chlorine level and staying that way for weeks

    Quote Originally Posted by tim5055 View Post
    Could the test kit be old/expired? That would be my first guess. I hope you understand that it is scientifically impossible for chlorine to stay in the pool for as long as you describe. The OTO test has a limit of 5 for chlorine (the 10 is for Bromine, using the same tube/scale).
    Can you provide the “scientifically impossible” reference?
    Thanks

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    Re: Way too high chlorine level and staying that way for weeks

    Quote Originally Posted by CaveDiver1932 View Post
    Can you provide the “scientifically impossible” reference?
    Thanks
    If you want all the down and dirty, you can read it here: Pool Water Chemistry

    The half life of HOCl/OCl (chlorine) - is 35 minutes. When you add CYA (which the OP is adding thru use of tabs) the chlorine becomes a chlorinated cyanurate which slows the degradation, but does not eliminate it. Had the OP said the high FC was being read over several days it could be possible, but even at astronomical CYA levels chlorine would go to zero in 5 weeks with no additions of chlorine.

    Chlorine is a consumable product.
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    Mod Squad zea3's Avatar
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    Re: Way too high chlorine level and staying that way for weeks

    I would like to add that you can see a residual chlorine level in a closed, covered pool with water below 60 degrees. Once the water temperature rises above 70 degrees and has exposure to uv rays the chlorine will degrade at normal rates.
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    Re: Way too high chlorine level and staying that way for weeks

    Tim,
    Richard (chem geek) is an invaluable resource for your forum. I spent about five minutes glancing through a few of threads embedded in the link you referenced. I did not find any reference that it is scientifically impossible for chlorine to remain in a pool for weeks. Actually, it appeared Richard was addressing breakdown rates of chlorine differences reported by other members specifically concerning cya. There are several factors that can impact longevity of chlorine. Temperature indirectly affects the breakdown of free chlorine. For example, bad characters (bacteria and algae - (most not all)) grow/multiply better in warmer water resulting free chlorine being “used up” faster than cold water. Another example is UV, in North America the angle of the sun is lower (low in the sky) this time of year which results in lower UV intensity resulting in a lower rate of free chlorine breakdown. I believe Richard addressed the cya impact. I doubt any of these relationships are linear.

    It is not unreasonable to expect a pool with a free chorine in the low to mid 20’s ppm with all chlorine sources removed and still have 3-10 ppm free chorine 4-6 weeks later this time of year especially with high cya with Low UV and water temps in the 50’s.

    If a gallon of bleach 10-13% is poured into a bucket and that bucket is placed direct sun in August, it would breakdown very quickly.

    Cheers
    Cd

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    Re: Way too high chlorine level and staying that way for weeks

    I had to use the pool store's test in order to provide a complete read out. I've interacted with this guy at my local Leslie's Pool store. He's a good guy. He rinses all the equipment with my water for each test.

    So...whatcha guys think? By the way, I really appreciate your expertise and sharing your time. Cheers.

    Free Available Chlorine = 10 ppm
    Total Available Chlorine = 10 ppm
    Calcium Hardness = 670 ppm <--- San Jose, CA is known for hard water...
    Cyanuric Acid = 120 ppm
    Total Alkalinity = 100 ppm
    pH = 7.4
    Copper = 0
    Iron = 0
    Total Dissolved Solids = 1050
    Phosphates = 50

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    Re: Way too high chlorine level and staying that way for weeks

    Did he say your chlorine was over max for the test kit? Some of these guys will record the max or 10 when reading exceeds the max of the test kit. As for the cya, most of the scales for the test kits they use max at 100. Some testers at that chain make a best guess which is not so close. Most don’t know about dilution methods. What is the temp of your pool water?

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    Re: Way too high chlorine level and staying that way for weeks

    Quote Originally Posted by CaveDiver1932 View Post
    Did he say your chlorine was over max for the test kit? Some of these guys will record the max or 10 when reading exceeds the max of the test kit. As for the cya, most of the scales for the test kits they use max at 100. Some testers at that chain make a best guess which is not so close. Most don’t know about dilution methods. What is the temp of your pool water?
    I failed to ask the clerk about how much the chlorine was over. But, in my experience of testing (20 years....yes I am just a homeowner), my guess would be 10 - 15. Just a guess, however. The water temp. is 61' F. AND yes, the clear did say the Cyanuric Acid reading was a guess because his test kit maxes out at 100. Ugh...

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    Re: Way too high chlorine level and staying that way for weeks

    You could dilute a sample with a controlled amount of distilled water see what readings the store gets. What you are seeing is not a surprise to me.

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    Re: Way too high chlorine level and staying that way for weeks

    Yea, he was probably using a DPD test kit which maxes out at 10 for FC and the CYA test maxes out at 100 as has been pointed out.

    The moral to the story is that at colder water temperatures the FC does go down much slower. I freely admit that I saw California and assumed nice warm water in southern CA, with maybe a margarita or two on the table. My geography of California is poor, I had no idea you were in the bay area.

    I'm going to guess your FC was much higher and is slowly going down due to the colder water temperatures.

    It's up to you, but we would still recommend that you get a test kit that allows both precision and a higher upper end on the FC test. The FSA/DPD test found in both the TF-100 and K-2006-C fit that bill. Additionally, I would recommend that you think about some water exchanges to get that CYA down into a more reasonable range. Plus you may need to reconsider your method of chlorination moving forward as the tabs are almost 50% CYA and only add to the ongoing problems.

    With water temperatures in the mid 50's I generally only add a little liquid chlorine every couple/few weeks.
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    Re: Way too high chlorine level and staying that way for weeks

    Hello all, thanks for the responses. Let me summarize my understanding and the next steps:

    1. Get a better test kit. Done. Easy.

    2. Drain the pool by 1/3 and refill.

    3. Start using liquid chlorine during the colder months. I'm thinking when it's 65'F or lower.

    Anything else I need to get my pool in good order? The FC has been this high for over 5 weeks without any more floating 3" tabs.

    P.S. All my pool lights are out (guessing the bulbs need replacing). Should I take care that while they are out of the water?

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    Mod Squad kimkats's Avatar
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    Re: Way too high chlorine level and staying that way for weeks

    I think it might be a good idea to change the bulbs so your don't freeze your hands/arms off in the burrrr water. I would make sure the cords are still good before I bought new bulbs though.

    What test kit did you get. There are videos to help with the testing if you need it. They CYA one can be the trickiest. The main thing is to GLANCE in the tube instead of staring to find the dot. Glance in then look away. If you don't see the dot at a glance then pour to the next line.

    Kim
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    Re: Way too high chlorine level and staying that way for weeks

    @kimkats so, draining the pool and refilling with fresh water is the only fix to my pool, right?

    Quote Originally Posted by kimkats View Post
    I think it might be a good idea to change the bulbs so your don't freeze your hands/arms off in the burrrr water. I would make sure the cords are still good before I bought new bulbs though.

    What test kit did you get. There are videos to help with the testing if you need it. They CYA one can be the trickiest. The main thing is to GLANCE in the tube instead of staring to find the dot. Glance in then look away. If you don't see the dot at a glance then pour to the next line.

    Kim

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    Re: Way too high chlorine level and staying that way for weeks

    Quote Originally Posted by cutaway View Post
    @kimkats so, draining the pool and refilling with fresh water is the only fix to my pool, right?
    To reduce your CYA, yes water replacement is the solution.

    But, until you get your test kit and we can figure out exactly what is really going on I wouldn't drain/refill more than 25%.

    In answer to your bulb question, while the water level is low is the time to do it. The actual housing (called a light niche) is flooded, but there is a sealed capsule that contains the bulb on the end of the light cord which is coiled up inside the niche. Most of the fixtures only have one screw holding the light in place. You lie down on the pool deck and reach down the side and remove the screw (it's usually on the bottom of the retaining ring) being VERY careful not to drop the screw. Once the screw is loose you can uncoil the cord and bring the housing up onto the pool deck to make the bulb change. It would help if you can identify the make/model of the fixture as the sealed capsule with the bulb generally has a seal that should be replaced when you change the bulb.
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    Re: Way too high chlorine level and staying that way for weeks

    Order #1543477265-352. I will post the test results from TF-100 as soon as possible. Thanks.

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