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Thread: what should CSI be?

  1. Back To Top    #1

    Join Date
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    what should CSI be?

    My water test results are as follows:

    fc 4
    cc0
    tc4
    ph 7.5
    ta 80
    ch 340
    cya 50
    salt 3800
    temp 84

    I have never added borates. When I enter this in pool calc it says my CSI is -.26, what does this mean? The chart says -.6 or less is bad for plaster, and .6 is bad for all pools. Should I do something?
    DONE, 20 x 40, inground gunite, 30" raised bond beam with 3 12" sheer descents, 8' diving board, pentair 420 cartridge filter, vs-3050 pump, intellechlor ic-40, auto cvr, Tahoe blue pebble tech, 6ea 4' x 12.5' & 2ea 1' x 12.5' helicol solar panels, legend robotic cleaner.

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    linen's Avatar
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    Re: what should SI be?

    I am assuming the SI you are refering to is actually CSI? CSI stands for Calcite Salturation Index which is a measure of how much risk you are at for scaling or pitting (mostly for plaster pools). If you keep your ph a little higher, that will get you away from the -.6 area, or if you raise TA a little.

    Before that though, what is your CYA level?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: what should SI be?

    Even with a cyanuric acid of 100 ppm, I am getting a CSI of -0.37 using the numbers that you posted.

    I like to keep plaster pools closer to a CSI of 0.0, although that can cause the salt cell to scale. I would say to keep it as close to 0.0 as possible without causing excessive scale in the cell. Perhaps allow your pH to go up to 7.6 or 7.7. Adding borates to 50 ppm will help reduce scaling in the cell and will allow the CSI to be kept a little bit higher. Maintaining a cyanuric acid level of 60 to 70 ppm will also help reduce cell scaling.

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    Re: what should CSI be?

    Edited my first post to include cya level. I have another pound of cya that I've contemplated adding which should get me to approx 60 on the cya level.
    For some reason I thought a lower ph was better so I've been keeping it in the 7.2 / 7.5 range.
    I'd like to to the borate thing but I've got a lab that drinks while he swims, alot, my guess is he drinks approx 1/2 gal when he's swimming for several hours, so I did'nt want to posion him.
    DONE, 20 x 40, inground gunite, 30" raised bond beam with 3 12" sheer descents, 8' diving board, pentair 420 cartridge filter, vs-3050 pump, intellechlor ic-40, auto cvr, Tahoe blue pebble tech, 6ea 4' x 12.5' & 2ea 1' x 12.5' helicol solar panels, legend robotic cleaner.

  5. Back To Top    #5

    Re: what should CSI be?

    If you're not getting a lot of scale in the cell, then you could allow the pH to go to 7.6 or 7.7, but watch for cell scaling and back off a little bit on the CSI if the cell scales up.

    Raising the cyanuric acid level to 60 ppm will help. Borates are not necessary, so if you're concerned, then it's better to leave them out.

  6. Back To Top    #6

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    Re: what should CSI be?

    Re entered #'s in pool calc and came up with -.26 csi, not sure what I did the first time. I can see that lowering th ph really lowers the csi so I'll try to keep my ph 7.5 / 7.7 now. I'll add the other lb. of cya also. Thanks for the help.
    DONE, 20 x 40, inground gunite, 30" raised bond beam with 3 12" sheer descents, 8' diving board, pentair 420 cartridge filter, vs-3050 pump, intellechlor ic-40, auto cvr, Tahoe blue pebble tech, 6ea 4' x 12.5' & 2ea 1' x 12.5' helicol solar panels, legend robotic cleaner.

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