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Thread: FC goal when using an Ozonator

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    FC goal when using an Ozonator

    My newly constructed pool was filled on Friday the 10th. The pool construction guy initially set up all the equipment, added CYA, and put two 3" tabs of trichlor in the automatic chlorinator. I was told that due to the QuikPure 3 25k gallon ozonator, my free chlorine levels would always be low (0.5) but effective at that level.

    When I had my water tested at a pool supply store on Friday, they showed:
    TC: 0.2, FC: 0.0, ph: 8.7, TA: 110, CH: 92, CYA: 40

    It was suggested I add muriatic acid and shock the system using 2 pounds of calcium hypochlorite, which I did between 5-6pm local time yesterday (the 17th).

    Today (the 18th) at 11am, I re-tested and see:
    TC: 8.0, FC: 5.9, ph: 7.6, TA: 107, CH: 132, CYA: 45

    ph is better, and FC is up... but there's a LOT of CC still left in the pool. That seems to indicate to me (the novice) that there wasn't enough chlorine in the pool over the past week (its first week of use), or the ozonator isn't working. Am I correct? What should my FC be with 25k gallon ozonator on a 14,300 gallon pool?

    Secondly, the pool supply store recommended I reshock again tonight to clear out the remaining CC. Is that good advice? Note that I bought CalHypo before I read about the BBB method here, and intend to use bleach for shockings going forward.

    Thank you in advance for any advice you can offer!
    My details: 16x32+swimout, 14,300 gallon, gunite/plaster pool, Jandy CL460 cart filter, 1.5 hp Stealth Pump, QuikClean six zone in-floor cleaning system, QuikPure QP3-25 Ozonator

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    frustratedpoolmom's Avatar
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    Re: FC goal when using an Ozonator

    Have you read this article on new plaster pools:
    http://www.troublefreepool.com/pool-...aster_start-up

    First off, let me start by saying I'm biased against Ozonators. I think they are unneccessary in an outdoor pool: Ozone destroys CCs - but so does sunlight (for free).

    Your FC level should be based on your CYA level - 2ppm at the very least - refer to the CYA chart in my sig. Even if you determine the ozone unit is functioning, .5 is simply too low to keep the pool properly sanitized.

    Now what I'm not sure about, since this is a new plaster pool, is the CC level (it seems odd to me to have such a high level already (I assume your water is clear), even after a week of low chlorine, and I'm wondering if your water supply uses monochloromines? Have you tested your tap water? Is the water clear?

    I don't know the "rule" for shocking a new plaster pool, if that's safe, because the article says "slowly". But I'm not sure if that has more to do with a reaction with metals, causing the plaster to stain....

    You can use cal-hypo for chlorine for awhile, to raise your CH level as well, 92 is too low, but I don't know if it's too early to raise the CH level - since this is new plaster....I don't think you're supposed to adjust the CH level for a month?....

    (As you can tell I don't have a lot of experience with these issues combined with new plaster...)

    Hopefully someone with more experience regarding new plaster and your issues will advise shortly....
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    JasonLion's Avatar
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    Re: FC goal when using an Ozonator

    Welcome to TFP!

    You want to keep your FC level at shock level, see this chart, until the CC level comes down. Shocking isn't a problem with fresh plaster unless you have metals in the water. If you suspect that you have metals, you should raise the FC level slowly and have extra sequestrant on hand.

    I don't recommend ozone systems for outdoor residential pools. None the less, if the ozone system is working, you should be able to run with a slightly lower FC level than we normally recommend, as long as nothing is going wrong. Because you are having a problem with high CC levels right now, that situation does not apply and you need to keep the FC level up until things settle down. Even when the CC level has dropped and you are done shocking, you should lower the FC level slowly and keep an eye out for problems starting.

    The key thing with fresh plaster is to keep the PH under control. You need to be testing the PH daily and adjusting it as needed. If the PH gets too high you can have calcium scaling, which is unsightly and expensive to repair.

    Longer term, you will be much better off if you get your own top quality test kit. That will save you money in the long run and prevent problems from happening in the first place.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: FC goal when using an Ozonator

    Quote Originally Posted by JasonLion
    I don't recommend ozone systems for outdoor residential pools. None the less, if the ozone system is working, you should be able to run with a lower FC level than we normally recommend, as long as nothing is going wrong.
    At best I think that the SWG level of FC might work, but with some algae that can stick to pool surface and not get circulated, the ozonator might not help very much. As you say, one can experiment and see -- first symptoms of too low an FC include a higher chlorine demand, then dull water, then cloudy and finally green (depending on type of algae).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: FC goal when using an Ozonator

    Quote Originally Posted by frustratedpoolmom
    Have you read this article on new plaster pools:
    http://www.troublefreepool.com/pool-...aster_start-up
    Thanks for that reference. My pool builder said that some of the steps involved in a normal plaster startup weren't needed due to the application of McGrayel's StartupTec. It's supposed to inhibit the production of plaster dust and make the pool inhabitable in 3 days. I used it, and so far, even with my present CC problem, the pool water is sparkling clean. I had very little dust after the first day of running the pump/filter.
    Now what I'm not sure about, since this is a new plaster pool, is the CC level (it seems odd to me to have such a high level already (I assume your water is clear), even after a week of low chlorine, and I'm wondering if your water supply uses monochloromines? Have you tested your tap water? Is the water clear?
    My tap water was clear... and the first test I did had very low TC. I assume that if my water supply had monochloromines, I'd have a high initial TC, right?
    Quote Originally Posted by JasonLion
    You want to keep your FC level at shock level, see this chart, until the CC level comes down. Shocking isn't a problem with fresh plaster unless you have metals in the water. If you suspect that you have metals, you should raise the FC level slowly and have extra sequestrant on hand.
    That's very useful. I'll try to stick to that FC level for now. I don't believe I have a problem with metals in the water supply.
    The key thing with fresh plaster is to keep the PH under control. You need to be testing the PH daily and adjusting it as needed. If the PH gets too high you can have calcium scaling, which is unsightly and expensive to repair.
    That's also something I didn't realize until today. As I noted above, my ph level was initially pretty high. It didn't appear that I had any scaling in the pool, though. It's still as smooth as it was when I first got in on Monday this week. I will test daily though to ensure it doesn't get outside of the recommended range.
    Longer term, you will be much better off if you get your own top quality test kit. That will save you money in the long run and prevent problems from happening in the first place.
    I'm also learning that now. I obviously should've done more reading on pool chemistry before now. Fortunately, there aren't any big problems yet, so I think there's still time to correct the errors of my way.

    Thanks for all the great advice!
    My details: 16x32+swimout, 14,300 gallon, gunite/plaster pool, Jandy CL460 cart filter, 1.5 hp Stealth Pump, QuikClean six zone in-floor cleaning system, QuikPure QP3-25 Ozonator

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    Re: FC goal when using an Ozonator

    Quote Originally Posted by chem geek
    At best I think that the SWG level of FC might work, but with some algae that can stick to pool surface and not get circulated, the ozonator might not help very much.
    I'm not sure if it makes any difference, but my 16x32 pool has a 6-zone QuikClean in-floor cleaning system built into it. To my untrained eye, the water appears to circulate quite well using that system. I haven't seen any cloudy water thus far. But I've also been brushing the new plaster twice daily, so I would imagine that keeps the algae from sticking better than anything.
    My details: 16x32+swimout, 14,300 gallon, gunite/plaster pool, Jandy CL460 cart filter, 1.5 hp Stealth Pump, QuikClean six zone in-floor cleaning system, QuikPure QP3-25 Ozonator

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    frustratedpoolmom's Avatar
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    Re: FC goal when using an Ozonator

    I don't know anything about "McGrayel's StartupTec" but I suspect there's something in that that's making the CC read high... what is "advanced multi-polymer blah blah blah...."

    A cursory glance tells me the mystery "trade secret polymer" could have a connection to your CC level....
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: FC goal when using an Ozonator

    To answer your original question: you need the same amount of FC regardless if you use an ozonator or not.

    Here are some facts about ozone (and I use one myself):
    1. For a 24000 gal pool you need about 7 grams/hr x 2 hours/day to oxidize the organic load. This ozonator will set you back about $10000. This is the biggest problem with ozone right now is it costs too much.

    2. Ozone won't prevent algae growth unless perhaps youhave #1 above and then it still may not since no one has totally figured out exactly what conditions make algae growths explode.

    3. Your ozonator was sold to you as a "supplemental sanitizers". This means it needs chlorine still. Yes you can sanitize with ozone and low levels of chlorine for a while until your pool explodes with an algae bloom and accumulates so much unoxidized and partially oxidized nonvolatile organics that you are swimming in a carcinogenic chemical soup... But your water may even be clear during this and you won't know it.

    So run the ozonator for now but manage the pool chemistry as if it wasn't there for now while you gain experience managing your water quality. With a fresh water fill you likely need to maintain the higher chlorine levels for weeks to months anyway till things settle down.
    IG 24k plaster with overflow spa. Goldline PS-8 SWG. Tristar 0.75 HP filter pump, Polaris 280, large cartridge filter, 400k BTU NG Max-E-Therm HD, SR Smith Turbo Twister, Life Saver pool fence, ORP managed.

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    Re: FC goal when using an Ozonator

    Quote Originally Posted by learthur
    So run the ozonator for now but manage the pool chemistry as if it wasn't there for now while you gain experience managing your water quality. With a fresh water fill you likely need to maintain the higher chlorine levels for weeks to months anyway till things settle down.
    Will do so. Thanks!

    I think I may have found the source of my CCs. The pool builder installed the leaf vac upside down... meaning the inflow comes through the bottom of the basket and out through the top. I knew about this, and it's supposed to be fixed soon. However, somehow, the basket was put back into place, and a giant dead frog (the size of my hand) has been stuck under the basket for a while now. I removed the basket (as it should be until the plumbing is fixed), cleaned it, and will now hope for the best.

    You live, you learn!
    My details: 16x32+swimout, 14,300 gallon, gunite/plaster pool, Jandy CL460 cart filter, 1.5 hp Stealth Pump, QuikClean six zone in-floor cleaning system, QuikPure QP3-25 Ozonator

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    Re: FC goal when using an Ozonator

    Hi ValleySoonerif at all possible could explain or take a picture of how your quikpure3 is hooked up. My brother-in-law talked me into it and I was able to get it for cost, so I bought it and never owning a pool before am not sure if it did great things or not. My pool was chrystal clear all last summer but I was crazy about my water. What I do know is that the air bubbles in pump housing and that blow out of my jets drive me insane! But I would hate to not use it for just those reasons, I was just curious if they hooked yours up with a stand pipe on the suction side before the pump?
    "There are no bad days, just some better than others"


    18k, Ig Vinyl, 3/4 us motors, Hayward sand filter, quickpure3 ozone generator

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