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Thread: High CH - Calcium Hardness level. CSI is fine. Reality check

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    bobodaclown's Avatar
    Join Date
    Apr 2011
    Murrieta, CA

    High CH - Calcium Hardness level. CSI is fine. Reality check

    Hello All,
    I've got my CYA level in line (80), got my TA down to 80 ish (might have to come down more). I was attempting to follow the pool level recommendations for a SWCG pool. CH max recommendation is 350, in my pool if it was that lowmy CSI level would be out of whack. CSI would be very low. Pool is concrete/pebble tech.

    I played with the pool calculator and realized the best way to bring the CSI to a more acceptable level would be to raise my CH - Calcium Hardness level up. I've raised my CH level to 525 and all appears to be going well. I'm running the CSI in negative numbers controlled by PH (7.4-7.8) CSI (-.32 - -.02).

    The pool water looks and feels great, the SWCG appears to be working fine not getting any noticeable scaling that I've needed to clean off. When it reverses polarity it seems to clear off any scaling. (Haven't had to do a manual clean/acid wash of the cell). The cell looks good no build up on the plates.

    This is my first 6 months of pool ownership and just checking that my logic/reasoning is normal.

    My though process is: maintain chlorine level based on CYA level, maintain PH between 7.5-7.8 (aerate to raise/acid to lower), tweak TA to control PH rise (add borates to assist in stabilizing PH if TA level is low which mine are), adjust CH to maintain CSI in proper range based upon PH range. Salt level keep it where it needs to be for the SWCG to function. Borates shoot for 50 raise back up when it gets to 30.) You have to test to know what's going on.

    Thanks for all recommendations in advance.
    Murrieta, CA. 15K (Est) pool/spa. Hayward Tristar SP3220EE 2.70HP pump, Hayward Swimclear Cartridge filter C4025 425sqft (PA106), Pentair Mastertemp 400 heater. TF-100/Speedstir

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: High CH - Calcium Hardness level. CSI is fine. Reality c

    Unless you have very high TA, or high CH, fill water, or some other unusual situation, it is best to simply ignore CSI, and focus on keeping your levels closer to the normal ranges we recommend.

    I would run CSI more negative that that. You are running a risk of scaling in the SWG cell if the PH goes up just slightly above normal. CSI inside the SWG cell is much higher than it is in the pool. Remember that PH goes up quite easily, but it is very unusual for it to go down on it's own. There is hardly any chance that PH will go below 7.4, while it is relatively likely that PH could go up to 8.0, or 8.2, or higher at some point during the season, perhaps during a moment of inattention or when shocking.
    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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