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Thread: How much Calcium it too much?

  1. #1
    Join Date
    Jun 2006
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    19

    Default How much Calcium it too much?

    Since a Vinyl lined pool does not need calcium, how much is too much and what kind of problems can it cause?

  2. #2
    Join Date
    Sep 2014
    Location
    Tucson, AZ
    Posts
    222

    Default Re: How much Calcium it too much?

    Typically you want to keep your calcium levels down below 500ppm. I'm in the southwest where the fill water is very hard (my fill water has 280ppm CH minimum). So after two + seasons, my water is at 600ppm CH.

    The main problem with high CH is the potential to scale or precipitate calcium onto your pool surfaces. The simple jingo for it is this - High pH + High TA + High Temperature is BAD. There is a parameter you can calculate called the Calcite Saturation Index (CSI) which basically describes the ability of your water to absorb or release calcium from solution. It's a logarithmic scale where -0.6 or lower means you water can be corrosive to a plaster surface (the water will absorb calcium) and where numbers larger than +0.6 means you water will potentially scale out calcium carbonate. All of your water parameters (pH, TA, CH, temperature, salt, borates, etc) all go into calculating the CSI value.

    The numbers are just rough guidelines but they give a good measure of your waters balance with respect to calcium. There are people with pools that have CH values over 1000ppm but they are still able to maintain scale-free pools simply because they adjust their other water parameters to compensate and they keep their CSI values negative. Eventually, if the CH gets high enough, you can't reasonably lower the TA or pH any further and then you need to consider other methods such as water replacement or reverse osmosis treatment to remove calcium build up.

    So there's no hard & fast rule that says a particular CH value is "too high" as it all depends on your other water parameters. You can find a VERY technical discussion of water chemistry and CSI calculations in this thread over at the TFP website
    16k gal IG gunite PebbleTec (Caribbean Blue), 18' x 36' free form with raised spa/spillway and separate rock waterfall. All Pentair Equipment pad - 3HP IntelliFlo VS / 1.5HP WhisperFlo, MasterTemp 400k BTU/hr heater, QuadDE-100 filter, IC40 SWCG, IntelliTouch/EasyTouch Controls

  3. #3
    Join Date
    Jun 2006
    Posts
    19

    Default Re: How much Calcium it too much?

    I havn't opened my pool yet this year. I know the calcium has been 190-220 the last few years and was curious if that in itself caused any problems like clogging filters.
    It doesn't sound like I need to worry about it.
    Thanks!

  4. #4
    Join Date
    Sep 2014
    Location
    Tucson, AZ
    Posts
    222

    Default Re: How much Calcium it too much?

    Quote Originally Posted by LearningCurve View Post
    I havn't opened my pool yet this year. I know the calcium has been 190-220 the last few years and was curious if that in itself caused any problems like clogging filters.
    It doesn't sound like I need to worry about it.
    Thanks!
    I'd kill for 220 CH (kidding, of course!)...yeah, you've got nothing to worry about with numbers like that. I think you mentioned you have a vinyl pool. CH is really a water parameter that liner pools don't need to worry about. Perhaps if it were 0ppm or below 120ppm and you had a water heater, some might say you should raise it a bit, but other than that, most liner pool owners don't even bother testing for CH. Plaster pools are a different story.

    Good luck with your opening when you get to it and enjoy the swim season wherever you are....
    16k gal IG gunite PebbleTec (Caribbean Blue), 18' x 36' free form with raised spa/spillway and separate rock waterfall. All Pentair Equipment pad - 3HP IntelliFlo VS / 1.5HP WhisperFlo, MasterTemp 400k BTU/hr heater, QuadDE-100 filter, IC40 SWCG, IntelliTouch/EasyTouch Controls

  5. #5
    Join Date
    Oct 2013
    Location
    Rhode Island
    Posts
    46

    Default Re: How much Calcium it too much?

    Just curious why the heater manufacturers recommend higher CH levels? Is it really necessary to increase CH in a AGP for the sake of the heater?
    Sharkline Escalade RTR 24' x 54" Round AGP; OptiFlo 2-speed pump; Pentair PLM-100 Cartridge Filter; Hayward 250FDN Heater; Taylor K-2006; AquaIlluminator Return

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