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Thread: Using chlorine/stabilizer pucks

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    Using chlorine/stabilizer pucks

    I am about to go on an extended 3 weeks trip during which I will have somebody else keeping an eye on the (40,000 ltr) pool. I believe I have got my CYA levels down to around 25 (will double check tomorrow). I am hoping this will allow me to add chlorine/stabilizer pucks to the skimmer to provide a continuing source of chlorine in my absence & minimize the frequency of topping up with liquid chlorine. Is there some equation that roughly describes the amount of chlorine & stabilizer released from pucks over time?

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    JoyfulNoise's Avatar
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    Re: Using chlorine/stabilizer pucks

    For every 10ppm of FC added by trichlor, you add 6ppm CYA. A standard 3" trichlor puck (99% purity) is approximately 8oz.

    You should not leave trichlor picks in the skimmer. They are acidic and the constant low pH load into the pump/filter/heater can damage your equipment. Get a puck floater instead and use that.
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    needsajet's Avatar
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    Re: Using chlorine/stabilizer pucks

    Pretty much have to test over a period of time to know. Depends on flow, but don't put pucks in your skimmer. They will make a horribly acidic chlorine stew when the pump is off.

    Get a floater or two and tie them in place so they don't rest against the side of the pool somewhere.

    If you have good records of consumption, and someone to check on the pool, pre-measured jugs of chlorine might be an option.

    If you create a signature including your pool details, you'll get the best possible advice here. Link with instructions is in my signature "Read before posting"

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    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    Thanks for the replies.

    Is it OK to use floaters under a solar blanket? While I'm away, the solar blanket would be on the pool most of the time. In the past, when I have had pucks in the skimmer, the pump has been running all the time. I don't have any kind of timer on the pump , I turn it on & off manually - is there a simple, inexpensive timer that I could add?

    10ppm of FC for 6ppm CYA doesn't seem like a very good ratio, but doesn't really help with the rate of release of the FC from the puck. I'm not sure I have enough time to conduct a thorough test.

    Over the past few weeks I've been adding about 1 litre of 10% liquid chlorine each evening, but the CYA seems to have dropped quite a bit in that time, so I'm thinking I may be able to reduce the chlorine additions to 1.5 litres every 2 days - which would be less of a burden on the volunteer "pool minder".
    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    Re: Using chlorine/stabilizer pucks

    Floater under a blanket is fine (it releases near the bottom, and blanket will probably hold it in place as well)

    Pucks won't hurt as much in the skimmer if the pump runs 24/7 (make sure pool minder tops up the pool if needed)

    If your liquid chlorine is pre-measured in old jugs with dates written on them, that's pretty easy I think
    - if you're short on jugs, you could write "half this jug on Jul 20, the rest on Jul 22"

    As far as quantity, 1 litre of 10% liquid chlorine is 2.5 ppm FC per day in a pool of 40,000 litres
    So using Canadian Tire Aquarius 200 g (3") Super Pucks (trichlor), each puck would add 4.6 ppm FC and 2.8 ppm CYA, so that's one new puck every other day, and your CYA would be around 50/60 when you get back.

    If pool minder wouldn't mind having a swim, maybe you could get them to to pull the cover off now and then and let the pool breathe (and the sun burn off some CC).
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    I have a large plastic measuring cup I think I got at a home improvment store. It's marked in both Imperial and Metric. In the past I've had the dog minder dump X oz of bleach in the pool every day. I know the level will be high, but bleach is cheap.
    27' Round Might Sun AG Pool 18000 Gallon Intex Krystal Clear SWG Hayward Pump/Filter on a Timer

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    Re: Using chlorine/stabilizer pucks

    Did two more CYA tests today with one reading 28 & the other 22.

    FC this morning tested at 5 - 10 with Taylor kit & 5 with the chlorine drop test.

    PH tested at 7.8

    Took a water sample to the pool store a couple of hours later - they gave me the following readings:

    FC 2.47
    TC 2.83
    CC 0.36
    PH 8.2
    Hardness 234
    Alkalinity (with stabilizer correction) 101
    CYA 50
    Copper 0
    Iron 0.1
    Phosphate 355

    Not sure how to take this. The CYA test, in particular, seems a bit "approximate" & there is a significant difference between my quite low readings & the pool store's 50 ppm. The pool store recommended lowering the PH level a bit.

    The water has been clear for the last 3 weeks or so (before I received my F100 kit) - I have been keeping the FC levels at 5 - 10 ppm on the assumption that the CYA level was a little on the high side, but I still seem to have a very small amount of algae collecting at the bottom of the pool every few days - not really visible until I brush.

    I bought a floater & a pail of pucks, but I'm hesitant to start using pucks without knowing where the CYA level actually is.
    Any suggestions for how to proceed?
    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    needsajet's Avatar
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    Re: Using chlorine/stabilizer pucks

    Trust your own testing and results over the pool store every day of the week.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    Why would the pool store testing be inaccurate? They are a very big, long-established, professional outfit with an (apparently) high-tech computerized testing system. However, my testing shows FC levels in the 5 - 10 range & with the drop test this morning at 7ppm. My CYA levels, tested 3 times in the last 2 days are reading at somewhere between 25 & 28. If this is accurate, should I be lowering the FC levels somewhat &/or boosting my CYA? As I said, if the CYA levels are that low, this should allow me to use pucks to supply chlorine for a couple of weeks while I am away - no?
    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    Mod Squad pooldv's Avatar
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    Re: Using chlorine/stabilizer pucks

    Pool store testing is inaccurate for a number of reasons and has been proven here time and time again. Use the search function to read literally thousands of threads about people taking water samples to pool stores and getting different results from different stores from their own tests, etc. Sometimes pool stores will give results that are chemically impossible.

    Here are some reasons
    Poorly trained temp help
    Poor testing technique
    Don't care
    Poor lighting
    Didn't rinse out the last customer's water
    Poor calibration
    Lack of calibration
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    Re: Using chlorine/stabilizer pucks

    Yes, you've got enough headroom on your CYA to use pucks while you're away. Use a floater unless your pump is going to run 24/7. If the pool will not be used, and has a cover on it the whole time (and normally doesn't) I would reduce the daily replenishment somewhat. It's not possible to know how much without some testing to find out even roughly how much, so it's just a judgment call.

    Your FC level is a bit higher than you need for your current CYA level, but it's also not harmful in any way. At 60 ppm CYA (for example when you get back after using pucks) it would be about right.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    Quote Originally Posted by needsajet View Post
    Use a floater unless your pump is going to run 24/7.
    What's the reasoning behind this advice? My pump runs 10 hours per day, and I was able to easily dial in my chlorinator so that it could satisfy my pool's 2 ppm/day average chlorine demand (employed during out-of-town trips only). I really don't get all this floater business.
    20K gallon vinyl inground pool, Hayward Pro Series sand filter, 1 HP pump, Taylor K-2006

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    needsajet's Avatar
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    Re: Using chlorine/stabilizer pucks

    OP doesn't have an inline chlorinator that I'm aware of, and is considering pucks in the skimmer for vacation as one of his options.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    Poorly trained temp help
    Poor testing technique
    Don't care
    Poor lighting
    Didn't rinse out the last customer's water
    Poor calibration
    Lack of calibration

    I can't comment on what other people's experience has been & I have no way of knowing how accurate the readings provided by my pool store actually are, but I am dubious that any of the above points would apply. This is a very professional operation - there is no eyeballing of solutions or anything like that - as far as I can tell there isn't much of a subjective element to the testing at all.
    The process appears to be that a few drops of water are put with a dropper into a small disc-like plastic container which is then then placed in some kind of device (a centrifuge?) A minute later the computer prints out the results. It's hard to see how any of the above points, except possibly calibration, would enter into it.

    I think I may have an inline chlorinator ... but I've never used it. When I was using pucks, I was running the pump 24/7. As the pool is not heated (my heater gave out a couple of years ago & I found that I didn't really need it as the pool is not that big & gets plenty of direct sun) I nearly always put the solar blanket on at night & it generally stays on until someone wants to use the pool. As I don't have a timer on my pump, I think I would probably leave the pump running 24/7 during my absence.

    I was thinking I could shock the pool before I leave, leave the pump & the cover on & assume that all will be well for at least 5 or 6 days, during which time nobody would be swimming anyway. After that I could ask my pool minder to check the FC levels & add a puck or two to the floater as required. I am assuming that the pool shouldn't get too out of whack in three weeks following this regime. After 10 days away I will have friends staying at the house for a week - they could make adjustments, but I'm thinking it's not too realistic to ask them to do too much.

    One potential issue: I still seem to have small amounts of algae appearing every couple of days - barely visible until I brush the sides of the pool. Given that the CYA levels are testing quite low & the FC levels quite high, this is a bit disturbing.

    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    Re: Using chlorine/stabilizer pucks

    Quite a few of us here raise FC to shock level before leaving for vacation. Liquid chlorine is recommended if you do.

    Glad to hear your pool minder can test and adjust FC as needed.

    At some point you may get into doing your own testing. I hope you do, but to each their own. If you want to get rid of the algae once and for all, a drop-based FAS-DPD chlorine test kit is needed and this is an effective procedure: Pool School - SLAM - Shock Level And Maintain

    I share the negative perspective on pool store testing and the recommendations pool stores provide. For me, when I see a water test number expressed to 3 significant figures, I know someone is trying to bamboozle me. That level of accuracy is neither needed nor representative of the water in your pool, other than by chance, and it's hard to believe that their equipment would be calibrated frequently enough to add credence to that level of accuracy. But hey, to each their own, and I know test kits are expensive in Canada.

    Have a terrific vacation!
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    One other thing about why pool store testing is not accurate. The sample of water you brought them is old. FC is volitle, pH changes with time and temperature, light can mess with chemicals, etc.

    Doing it yourself at poolside is the best way to know for sure,

    One other thing you need to realize, the CYA test cylinder is not a ruler, it is a "less-than or equal to" device, meaning anything over one line is considered the next line. Your results of 22 and 28 are both 30. They were more than 20 but less than 30, so the number to record is 30.
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    Re: Using chlorine/stabilizer pucks

    I don't intend to use the pool store for water testing now that I have my TF-100 - it's not a very convenient option for me in any case, as the store is a 25 minute drive away. If their readings are not accurate it's a particularly unhelpful service - more like a placebo than anything useful.

    I appreciate everybody's input. My continuing dilemma is this: I seem to be one step away from algae formation all the time. Last night I didn't add any chlorine as my CYA levels appear to be low - below 30 anyway & my FC relatively high at somewhere between 5 & 10. I left the pool covered today & just now 6.30 pm took the cover off. There is a modest (but obvious) amount of algae on the bottom.

    My testing this evening shows:

    Water temp ca. 27c
    FC 5 - 10
    Drop test 5.5 FC
    CYA 30
    PH level 8.2 +
    TA 150
    CC 1

    Given the high levels of FC (relative to the CYA levels) that I have maintained over the lsat 3 weeks, I'm bit surprised that there is a persistent threat of algae. It appears as though maintaining a FC level in the 7 - 10 range has kept it at bay, but letting the FC level fall lower than that seems to result in some algae growth.

    So ... I now have 3 days before I go away to sort this out. I should apparently lower the PH level - I'm not clear what the effect of this will be. Beyond that, any suggestions as the best way to proceed over the next 3 days?

    Again - all suggestions are very much appreciated!
    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    Re: Using chlorine/stabilizer pucks

    A couple of things to think about.

    I suspect you've done enough reading here to know you're going to need to SLAM when you get back. Visible algae is all you need to make that decision. The cover may be harboring a fair bit of algae, and any other surfaces that aren't getting enough chlorine and brushing to kill algae.

    pH is very important. Available Chlorine (a small proportion of Free Chlorine) shifts to less hypochlorous acid (which is the most active form of chlorine) as pH rises. The correct range of 7.2 to 7.8 is where the chlorine works best. It's also the comfort range for swimmers. If you're at 8.2+, you have no idea how high it is (testing limit is 8.2). Use muriatic acid to bring the pH down into range. (see PoolMath and Pool School - Recommended Pool Chemicals).

    If it were me, I'd elevate chlorine to 12 ppm FC right away and keep it there until you leave, and brush regularly. Then adopt your plan for your absence, and SLAM when you get back.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Using chlorine/stabilizer pucks

    FWIW - the pool store reading was also 8.2 PH.

    I've been brushing regularly as every couple of days there has been a very small amount of algae on the (sloping) sides of the pool. I'll elevate the FC tonight. Is there any problem adding muriatic acid at the same time as the liquid chlorine?
    10,500 US gal, IG vinyl, Hayward pump, sand filter. TF-100

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    Mod Squad pooldv's Avatar
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    Re: Using chlorine/stabilizer pucks

    Add them 15 minutes apart. It is important to maintain PH between 7.2 and 7.8.
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