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Thread: What is the reason behind needing a higher CYA?

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    What is the reason behind needing a higher CYA?

    Could not find my answer through searching, and would like to add to the questions of OP. What is the reason behind needing a higher CYA value in the range of 70-80 for SWG?
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    Mod Squad JohnT's Avatar
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    Re: What is the reason behind needing a higher CYA?

    Welcome to TFP!

    It allows the SWCG to keep up with chlorine production without wearing the cell out prematurely. Different manufacturers recommend slightly different levels, but 70-80ppm is typical.
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    Re: What is the reason behind needing a higher CYA?

    I understand the reasoning, don't understand why it would not apply to liquid chlorine also. If my cya was at swg levels, wouldn't I have to add chlorine less often or at least not as much chlorine?

    Anthony
    Dallas area, free form, quartz finish, flagstone, pentair cartridge, vs pump, swg

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    Re: What is the reason behind needing a higher CYA?

    A lot of it has to do with the "evenness" or "constancy" that an SWG adds chlorine to your pool. If you could manually add liquid chlorine in tiny doses every ten minutes or so, you could successfully operate at 60-80 CYA.

    A peristaltic pump applies chlorine to a pool in much the same manner as an SWG and that can be operated with 60-80 CYA as well if your dosages are spread out very evenly in a 24 hour cycle.
    Dave S.
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    Re: What is the reason behind needing a higher CYA?

    Higher CYA levels reduce the total amount of chlorine you need to use, but they also cause secondary problems. For example at higher CYA levels if you do get algae the higher shock levels required make shocking much more of a project. As it happens, a SWG reduces the odds of needing to shock the pool, thus making it less likely that you will run into most of the negative effects of higher CYA levels. Having a SWG also greatly increases the costs of having a low CYA level, ie the cell needs replacing more often, the PH drifts more, and so on. So the balance point, where the benefits of CYA balance out with the costs is at a higher CYA level for SWG owners than it is for liquid chlorine users.
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    Re: What is the reason behind needing a higher CYA?

    Quote Originally Posted by duraleigh
    A lot of it has to do with the "evenness" or "constancy" that an SWG adds chlorine to your pool. If you could manually add liquid chlorine in tiny doses every ten minutes or so, you could successfully operate at 60-80 CYA.
    Would using a Liquidator allow you to realize the same benefits?
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    Re: What is the reason behind needing a higher CYA?

    Perhaps. Remember that the main downside to the higher CYA level is IF something goes wrong and you need to shock the pool. So to the extent that The Liquidator makes it less likely for the chlorine level to get too low, then yes it would make it a bit safer to allow you to operate at a higher CYA level. On the other hand, if you are very diligent about adding chlorine regularly, you could have the CYA higher with no problems. Some people pretty much have to do this because they live in such hot sunny areas that they simply lose too much chlorine if they don't keep the CYA higher. Pool services that only visit weekly are in a similar situation though they have the CYA level be even higher than we are talking about, usually 100+ ppm, but they have a large swing of chlorine level such as up to 14 ppm that then drops to 4 at the end of the week.

    Our recommendations are for what works for most pools most of the time. There are no absolutes here. If having a higher CYA level so that you use less chlorine every day is that important to you and you don't care about spending more money, then there are other ways of doing that by supplementing with other products or methods to prevent algae growth, but this deviates from the keeping-it-simple approaches we strive for on this forum.

    You could also look at your question the other way around. Instead of seeing higher CYA as a benefit due to lower daily chlorine consumption, you could see it as a problem increasing risk if anything goes wrong so in that sense it is the SWG systems being typically undersized that is part of the problem and that they aerate the water too much or outgas undissolved chlorine gas.
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