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Thread: rainwater dilution, negative csi.

  1. #1
    Senior Member
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    Feb 2011
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    Petaluma, Ca
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    rainwater dilution, negative csi.

    I wanted to lower the salt level in my pool and the CH some. My ic-40 is set at 8%, pump runs 8 hrs per day.I put the pump on the cover and the hose into the pool, we recieved approx 3" of rain. Here are the old numbers and then the new.

    fc 4.5
    cc 0
    tc 4.5
    ph 7.5
    ta 70
    ch 340
    cya 55
    salt 3600
    temp 63

    As of this am, I didn't check the cya.

    fc 4.0
    cc 0
    tc 4.0
    ph 7.4
    ta 60
    ch 290
    cya ???
    salt 3400
    temp 60

    The results were somewhat what I expected. I plan on adding another dose of cya to raise that some. My worry is now the csi is -.79. I know the value of csi is debated. Should I do something about it?
    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.

  2. #2
    Senior Member Richard320's Avatar
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    San Dimas, CA (LA County)
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    Re: rainwater dilution, negative csi.

    Let it mix some more and then recheck.
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  3. #3
    Administrator JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: rainwater dilution, negative csi.

    -0.79 us getting down there, and adding some CYA will take it lower. With TA that low, the PH isn't going to come back up very quickly, though it will come back up eventually. I suggesting raising the PH just a little, say to 7.6.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  4. #4
    Senior Member
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    Re: rainwater dilution, negative csi.

    So if I add baking soda I can raise the ta & the ph at the same time per the pool calc. To raise ta by 10 add 68 oz. Not sure how much the ph will rise. If I get the ta back to 70 and the ph to 7.6 I'll be at -.51 csi.
    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. #5
    Administrator JasonLion's Avatar
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    Re: rainwater dilution, negative csi.

    Baking soda has only a very small effect on PH, it should be better to use soda ash, at least if you have some.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. #6
    Senior Member
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    Feb 2011
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    Re: rainwater dilution, negative csi.

    I already had baking soda so I used that, added 80 oz. The new numbers are better as far as the csi goes, it's now -.51. It's always somewhat hard to get a good ph reading, it may be a little more than 7.5. I attribute the rise in ch to the water being mixed better today.If the water gets warmer that will help also.

    fc 5.5
    cc 0
    tc 5.5
    ph 7.5
    ta 70
    ch 310
    cya (was 55 before the addition of 3" of rain)
    salt 3400
    temp 62
    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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