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Thread: How low CH with diamond brite finish? 150?

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    How low CH with diamond brite finish? 150?

    Hi,
    I had the pool acid washed due to likely scale forming, even though the CH got only to about 400. The tap is CH of 80. I'm going to be super careful this year with all my numbers, but want to also run the CH as absolutely low as is safe, to help prevent the scale. I've read everywhere that "150" is the lowest I can go. Is this correct? I've started using the pool calculator, and putting in trial numbers---I can go a bit lower than that, and still have a safe "csi." Can I ask what you would recommend?

    Thanks.
    16,000 gallon, inground. Diamond bright finish. Hayward 1.5 hp superpump, quad 80 DE filter, Jandy legacy gas heater

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    BoDarville's Avatar
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    Re: How low CH with diamond brite finish? 150?

    Diamond Brite is considered plaster as far as the Pool Calculator is concerned. The ideal CH range for plaster is between 250 - 350 ppm. If the CH is too low in a plaster pool, the water can dissolve calcium out of the plaster.
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    JasonLion's Avatar
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    Re: How low CH with diamond brite finish? 150?

    It is not about keeping CH as low as possible, it is about keeping all of your levels balanced relative to each other. Because of your high fill water CH level, your CH is going to go up. There is nothing you can do about that. The key is to maintain all of your other levels so your CSI remains in the appropriate range. In your situation, you want to start CH a little low, and it will eventually get high. Then you adjust the PH and TA levels to compensate for your CH level (low or high). When CH is low you run PH & TA higher than normal, and when CH is high you run PH & TA lower than normal. You can use the Pool Calculator to find out what appropriate adjustments are.
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    Re: How low CH with diamond brite finish? 150?

    Thanks very much. Is it safe to say that as long as the pool calculator says the csi is safe (lets say +/-0.3) that i'm fine? I can at least start out at 150 CH , and possibly stay at 150 the whole year?
    16,000 gallon, inground. Diamond bright finish. Hayward 1.5 hp superpump, quad 80 DE filter, Jandy legacy gas heater

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    JasonLion's Avatar
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    Re: How low CH with diamond brite finish? 150?

    If there is any chance of maintaining a constant CH level, which seems rather unlikely, you do not want CH as low as 150. The only reason to lower CH that low is if you know for certain that it will go up, and want as much time as possible before it gets wildly too high.

    You generally want to aim for a just slightly below zero CSI level. PH has a habit of going up when you aren't paying attention, so you want to reserve some of your safe CSI range just in case the PH goes up when you aren't watching closely enough.
    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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