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Thread: Black Gunite pool has been prone to grow algae. New Refill

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    Black Gunite pool has been prone to grow algae. New Refill

    Over the last 4 years I've had several pool services and none have been able to keep my pool algae free, without a lot of effort. Pool is heavily used in North Carolina, and often has had 10-15 house occupants in the pool in hot weather.

    Following prior tips on this forum, am starting anew! again, as cya was sky high, due to over use of pucks.

    This year we are starting fresh with a thoroughly drained and cleaned pool and a fresh city water refill.

    The only things added so far was one shock with cal-hypo and some chlorine stabilizer.

    The latest results show The calcium level is cca 100 ppm. Ph is 7.4, alkalinity 60 ppm., chlorine at 5ppm, and cya at 30. not sure about calcium hardness? unless Ch is the same thing as cca?

    We plan to solely use which ever chlorine product that keeps cya the lowest other than liquid bleach..

    Summary:
    1. Do my levels sound ok, or adjustments might be needed?
    2. Is it ok to use Cal-hypo for lowest cya? (I choose not to haul liquid bleach, but know it's an alternative)
    3. Is algaecide recommended in my current situation with the fresh fill of city water, in view of our history of algae?
    4. Is there a down side to just using cal-hypo?
    5 Is CH the same reading as CCA? (newbie here)

    the pool and water are now perfectly clear.

    tips appreciated!

    PS. I have seen this post from 'chem expert' on this forum...
    For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
    For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
    For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.

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    Re: Black Gunite pool has been prone to grow algae. New Refi

    Is this a vacation rental house? Not nosey, but the advice will be different.
    Dave S.
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    harleysilo's Avatar
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    Have you considered switching over to a salt water pool with a salt water chlorine generator? No hauling bleach, no chlorine pucks...
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    It is a vacation rental, so the load is high.

    I plan to stick with chlorine, if I can find something that works reliably.

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    harleysilo's Avatar
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    No doubt you'll be sticking with chlorine, it's just the method of getting it into the pool that needs to be figured out.
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    It is difficult to manage a pool with liquid chlorine (the best chlorine) if there is not somebody there. I think you may already know that. Your only alternative that I can see is to use pucks, but YOU MUST MANAGE THE CYA.

    Pucks will provide adequate chlorine (but you'll need a lot) and algae cannot grow in the presence of adequate chlorine. That said, they will quickly add too much CYA to your pool and totally undermine the effectiveness of your chlorine.

    Unless you can go by the pool at the VERY least weekly (to accurately test your own water....don't trust any pool stores testing) you will not know when to drain some of your pool to lower cYA.

    Perhaps you can teach a pool service to follow your instructions but most will do it "their own way" which will almost always result in overblown CYA and algae..
    Dave S.
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    The pucks alone, approach has not worked. as mentioned the cya goes sky high.

    Given that, my question is whether cal-hypo alone will get the job done. My pool guy will go by either once or twice a week, but I wonder if that will be enough cal-hypo?

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    Re: Black Gunite pool has been prone to grow algae. New Refi

    Too much Cal Hypo overloads your CH and you will very possibly get calcium scaling AND cloudy water that can be a real pain. I would not consider it an acceptable method unless you drain it off occasionally.

    The pucks have not worked because they were not managed properly.
    Dave S.
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    Ok, so cal-hypo alone is not a good plan.

    Curious if some of the many pros on this great forum can tell me about a tried and true chlorine method that will work with weekly visits or twice weekly. (I'd prefer to avoid the liquid bleach unless it is the only choice)

    Could it be maybe half pucks and half cal-hypo?

    I'm guessing there may be many other combinations, but just don't know enough yet, but I know that we have to keep cya low!

    Many thanks for any advice!

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    Re: Black Gunite pool has been prone to grow algae. New Refi

    If you have a pool guy who goes by at least weekly, the pucks will work. BUT you have to make him test with a valid test kit (not strips and not the pool store) so he can drain and refill some water to keep the CYA in check. It's the slow release feature of the pucks that will allow you to keep adequate chlorine in your pool between visits.

    I'm sounding like a stuck record, but short of an SWG, pucks are your best alternative and CAN work just fine.
    Dave S.
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    I don't mind sounding like a broken record. SWG SWG SWG SWG SWG
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    Liquid chlorine every few days, liquidator or injector pump running off the pool timer. Have them top off the liquid bleach when they check on the pool.
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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    Re: Black Gunite pool has been prone to grow algae. New Refi

    As i mentioned before you should research SWG here pool-school/salt_water_chlorine_generators

    My only concern is dialing it iin and your pump run time in. And then if you have a week with no use in middle of summer, chlorine level might creep up if it's been optimized for heavy use. BUT if you got a pool guy coming buy that can be adjusted.
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    Re: Black Gunite pool has been prone to grow algae. New Refi

    I hear the Salt Water proposals, and I may consider that after all else.

    My guess is that there are hundreds of thousands of pools just in the US, many of which are being successfully operated with some type of dry chlorine, though most will be far lower usage than vacation rental houses!

    That notwithstanding, among these beach rental houses with pools with high use, we have 3 fiberglass pools which are mostly operated with pucks, and they do fine, even without draining and refilling.

    It's just two black gunnite pools that give us the hardest time. Some beleive the 5 degree higher temp in the summer may contribute to the algae problem.

    Before we invest in the Salt Water equipment, I'd love to hear if any experienced folks have any known, dry chlorine approaches which are likely to, or known to work on high usage pools in hot weather.

    Alternatively there a good chance that liquid 12% bleach will work if administered just Twice per week?

    Likewise how does maybe half pucks and half cal-hypo sound as a possible solution added twice per week?

    Before we 'dive' in would just like to check into all the feasible and practical solutions!

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    Re: Black Gunite pool has been prone to grow algae. New Refi

    It does not matter what form of chlorine you use ... as long as your FC stays high enough for your CYA level. If you are raising the CYA, then your minimum FC rises as well. If you are using cal-hypo, you have the additional concern of raising the CH too high which can lead to scaling.

    Once either the CH or CYA get too high, you will likely have to replace water.

    If you have a slightly elevated CYA, you can likely get by with adding bleach twice per week. You will just have to raise the FC level high enough such that it does not drop below the minimum before you come back.
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