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Thread: Is CSI a long term problem or a short term problem

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    ateam's Avatar
    Join Date
    Jul 2015
    San Antonio, TX

    Is CSI a long term problem or a short term problem

    I feel like I'm always working the edges of the allowable CSI levels. How much should I be worried about CSI? Is it a longterm neglect problem, or can limited time at or beyond the acceptable limits of CSI be harmful as well?

    Here are my test results:

    PH - 7.2
    FC - 8
    CC - 0
    TA - 100
    CH - 250
    CYA - 50
    NaCl - 1000
    Borates - 15
    Temp - 72
    CSI = -.49 (potential to become corrosive to plaster)

    I'm currently trying to lower my TA a little so I can add borates. That is why my PH is at 7.2. I have a waterfall so I'm always fighting rising PH. My fill water is also high in PH and TA so I keep MA on hand at all times.

    Pool looks great. I'm actually using the heater to warm it up a little for swimming this weekend.

    in-ground pool/spa with spill over, plaster/pebble, multiple waterfalls
    4x Pentair pumps, Pentair DE filter, Pentair Heater, Auto-fill
    Completed 2011, TF-100 test kit w/ Speedstir

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    TFP Guide

    chiefwej's Avatar
    Join Date
    Jun 2011

    Re: Is CSI a long term problem or a short term problem

    While I'm in the process of lowering the TA I often reach that kind of CSI and even lower. It doesn't stay there long, just until the aeration raises the pH. There is no cause for concern. Your pool won't dissolve overnight. In fact PoolMath lists the acceptable range as between +0.6 and -0.6, so you are comfortabilty within that range.

    When lowering my TA, I find that I get the best results by lowering pH to 7.0 then letting it rise to 7.5 before lowering again. That seems to work the quickest. Good luck with getting the pH to stabilize. I fight pH rise constantly. High evaporation, high TA fill water and SWG.
    Tucson, AZ
    16x36 rectangular (19k) Pebble Tec play pool/spa, Pentair Intelliflo VS 011018, Super II 2hp (spa), Aqua Rite T-15 SWG, Pro Grid 60 DE, H400 & Heliocol Solar, Dolphin S-300, fill water w/high CH and TA, 50 ppm borates,TF-100 test kit, Smart Home/Alexa pool control

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    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: Is CSI a long term problem or a short term problem

    Yes, agreed you are doing fine with your CSI and working on lowering your TA. If your heater has a copper heat exchange then be careful with pH below 7.0 for longer periods of time. Low pH will dissolve copper into the water over time. Keeping it 7.2 is safer.
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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