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Thread: My chlorine reading is 0 even after filling the chlorinator full

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    My chlorine reading is 0 even after filling the chlorinator full

    My CYA is no the high side (100) My problem is that my chlorine reading is 0 even after filling the clorinator to full and wide open on #5 then also adding 4 tablets to skimmer have been running the pump 24/7. Still no chlorine reading. Pool is clear and beautiful. FC is 0 CC is 0. ph is 7.2 TA is 100 CH is 160. One pool supply tells me to do nothing but wait for the TC to raise (it has been 10 days without getting a reading but did get to .03 one day) another pool supply says to drain 1/3 of the water and refill to lower the CYA. This I understand and also understand that the higher the CYA the more higher TC needed to sanitize. But I do not get why I show no TC at all. Where is all the chlorine going? I use Triclor and at first suspected that it had lost it's shelf life so the pool supply replaced it. When I put the knew pucs in the chlorinator the FC was 4 the next day but the following day it was 0. Also replaced the reagents. So the questions are..why am I not getting a reading, or what is eating the chlorine and if I go ahead and drain and refill getting the CYA down can I then expect to get a chlorine reading? Do I need to shock or drain and refill or do both? Nobody at either pool supply really knows the cause or what to do.

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    Mod Squad jblizzle's Avatar
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    Re: My chlorine reading is 0 even after filling the chlorina

    Start reading Pool School sounds like you have started to learn a bit about FC/CYA relationship.

    You need at least a 50% drain and refill but in reality your CYA may be even higher. You need a good test kit and to stop using pucks or you will continue to struggle with keeping enough FC in the pool. My guess is that you are pretty close to having your water change from clear to green.

    When you have a test kit, post a full set of levels and we can guide you .. likely through a shocking process.

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    Re: My chlorine reading is 0 even after filling the chlorina

    Most likely, the chlorinator is clogged, or the reagents are bleaching out due to high chlorine. Try an OTO chlorine test, as OTO does not bleach out.

    Caution, if the feeder is clogged, then the feeder could be dangerously full of chlorinated gas. Only open it if you feel that you can do it safely. If you don't feel comfortable opening the feeder, have someone else do it who does feel comfortable.

    How many gallons is your pool?

    How many tabs did you put in the feeder?

    What are you using to test the chlorine?

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    Re: My chlorine reading is 0 even after filling the chlorina

    So the questions are..why am I not getting a reading, or what is eating the chlorine and if I go ahead and drain and refill getting the CYA down can I then expect to get a chlorine reading? Do I need to shock or drain and refill or do both?
    It is possible the chlorinator is clogged but more likely that you have algae in the pool that you cannot see. What is likely happening is a balance of algae growing and just enough chlorine to kill some of it but not enough to wipe it out.

    As stated above, the pucks are your enemy. Stop using them, drain/refill to get CYA down to 40-50, and yes, then shock the pool and you will EASILY be able to hold a chlorine reading.

    After your drain/refill, be sure to use the shock process exactly as it is described in Pool School.
    Dave S.
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    Smykowski's Avatar
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    Re: My chlorine reading is 0 even after filling the chlorina

    Quote Originally Posted by duraleigh
    So the questions are..why am I not getting a reading, or what is eating the chlorine and if I go ahead and drain and refill getting the CYA down can I then expect to get a chlorine reading? Do I need to shock or drain and refill or do both?
    It is possible the chlorinator is clogged but more likely that you have algae in the pool that you cannot see. What is likely happening is a balance of algae growing and just enough chlorine to kill some of it but not enough to wipe it out.
    Also remember, the reaction between FC in the pool and organics occurs in minutes. So, if you have enough "stuff" growing in the pool, the pucks are putting chlorine in the pool, but less than 10 minutes later, it's all ready used up.

    (I have chem geek to thank for the chemical reaction part of my education here)
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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    Re: My chlorine reading is 0 even after filling the chlorina

    Thank you for responding. We have drained about 30% of the water and are now refilling so will be balanceing the pool again. Readings before the drain were fc 0 cc 0 ph 7.2 ta 100 cya 100 ch 160. Guess all that is not relavant now. Chlorinator does not seem to have a build up of gases and the 6 tablets are put in there with the chlorinator wide open, have only dissolved about half. I would have expected more. Is the check valve that screw at the bottom of the chlorinator? And is that what I need to check and possible change? I would love to quit using the stabalized chloride tabs and change to liquid. I think I can get the stronger bleach at lowe's and if not I will have to use the weeker one the the grocery store carries as none of our pool supplies carry liquid chlorine. How much of that is needed as a maintenence dose and how often do I have to add it? Do I shock with it? My pool is about 19,500 gal. (18x32 ft and 8ft in deep end and 3ft in shallow). We have a sand filter and the pump is 3/4 HP. Also will I need to be using acid to bring down the ph if using liquid? What do you think about using calcium hypochlorite as maintence and shock? I do not have the super duper test kit to tell me chloring level above 5. Do you think that 2 lbs. of calcium hypochlorite is enough to shock with or do I need more to bring the level high enough? I am thinking that the chlorine should hold a reading after super chlorinating. Pool temp is 70 by the way and is clear and sparkling.

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    Mod Squad jblizzle's Avatar
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    Re: My chlorine reading is 0 even after filling the chlorina

    You need to continue reading Pool School (see my signature) as most of what you have asked is addressed there.

    Start with ABC's of Pool Water Chemistry. Cal Hypo will not add CYA, but it will add CH which can also cause problems when it gets too high. Stick with liquid chlorine for maintenance and the shock process see:Shocking Your Pool

    If your CYA is 100ppm (likely higher as the tests usually stop there). Your MINIMUM FC level is 7ppm. See Chlorine CYA Chart. So with your test kit there is no way to know if it stops at 5ppm.

    You can use poolcalculator.com to estimate what dosages are required, but you need the ability to test.

    Get a good test kit and keep reading.

    I am happy your water is clear, but fear it may not stay that way if you do not get your CYA under control and maintain adequate FC using liquid chlorine.
    Jason, TFP Moderator
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    Re: My chlorine reading is 0 even after filling the chlorina

    Does your system include an ozone generator?

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    Re: My chlorine reading is 0 even after filling the chlorina

    no, no ozone generator. I don't know what that is.

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