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Thread: First real tests

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    First real tests

    So we opened our pool today - and the water didn't look too bad. The numbers, of course, need some work!

    We're planning on switching to SWG in the next few weeks - I don't know if that affects what I do based on my test results right now or not. This is my first time using the TF-100 test kit and these numbers were after I'd had the pump going for about an hour or so. My water level is a little high - we've had so much rain over the last few weeks - and at this moment, the water level is only below the top of only one of the skimmers (one skimmer is higher than the other). I'll be dropping that down some more tomorrow.

    My concern is the CYA - according to the pool calc, I need to replace 60% of my water. Eek! I'm hoping there is a way around that... I know now that this is so high because of the chlorine pucks we used (and have probably been used for years, we just bought the house last year).

    Here are my numbers -

    FC 9.5 (when we opened the pool we added two gallons of chlorine, this number was a couple of hours later)
    CC 0
    PH 7.2
    TA 50
    CH 150
    CYA ~100

    I've not added anything so far other than the chlorine mentioned. I put the numbers in The Pool Calc so have some idea of what's coming but thought I'd see whether moving to salt will change anything I do.

    Thanks!
    19x43 Inground Vinyl Pool, approx 22 years old, no main drain, 2 (lopsided!) skimmers, 2 returns.
    1 HP Pentair Superflow Pump
    27" Hayward Sand Filter
    AutoPilot SWCG
    Aquabot T-4 Cleaner

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    Richard320's Avatar
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    Re: First real tests

    You can maintain the pool with CYA that high. I've done it. I inherited CYA somewhere in the 220-240 range. But I'll tell you, it gets old having to use the FAS-DPD test every time, and always wondering if the pH reading is correct or not, given the necessarily high FC level. I've been operating under water restrictions (although Moonbeam declared the drought is over, so maybe that's over too) so I couldn't just drain out enough and start over. Well, I could have, but it would have put me way into Tier 3 rates, and possibly earned me a flow restrictor on my meter, which gets billed to the owner, as well. Over the course of a year, through lawn watering and rainwater dilution, I finally have CYA in range.

    If you have no water restrictions, I'd say, drain & refill. It will buy you some working room should you develop some algae later on.

    By the way, you might want to mix some tap water 50/50 with pool water, then use that mixture with the CYA test and double your reading. You might be higher than 100. You'll need to be sure so you drain enough water.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    JasonLion's Avatar
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    May 2007
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    Re: First real tests

    Do the CYA test again with a 50/50 mix of pool water and tap water and double the test result. Then replace enough water to get CYA under 100. You really don't want to be trying to maintain a pool with CYA at 100+.
    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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    duraleigh's Avatar
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    Re: First real tests

    I know Richard320 has managed his pool with that high CYA but I also know from his other posts that he is pretty meticulous and attentive to his pool.

    So while it can be done, I would only encourage it if your water situation is similar to his where you really CAN'T drain and refill.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: First real tests

    It's my understanding that the biggest problem with high CYA is being able to maintain the proper FC levels. With that issue comes the issue of maintaining the proper ph. I also know (I think I do anyway!) that with a SWG you are better off with higher CYA (not as high as what I have right now though). Am I remembering correctly too that full sun means you want to keep your CYA on the higher end of normal also?

    If these things are all true, I'm wondering if I can do several smaller water replacements to try to work the CYA down a bit, but given we are adding the SWG in a few weeks - not feel the need to drop it as far as described on the PoolCalc? I know this will be slower than removing a large amount at once but I do have a couple of issues with a large draining. In the meantime, know that I'm going to have to monitor FC a lot closer. I've not yet added the salt. Figured it would be better to wait until I get some of these things under control since I'm going to be pumping some water out over the next week.

    How will CYA above 80-90 affect a new SWG?

    Thanks for the input and help - I'm trying to get all this figured out!
    19x43 Inground Vinyl Pool, approx 22 years old, no main drain, 2 (lopsided!) skimmers, 2 returns.
    1 HP Pentair Superflow Pump
    27" Hayward Sand Filter
    AutoPilot SWCG
    Aquabot T-4 Cleaner

  6. Back To Top    #6
    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    37,879

    Re: First real tests

    You should do the CYA test with dilution, as mentioned previously, to get a better idea of what your CYA level really is. If CYA is currently actually 100 then you can lower it slowly and live with it a little high, but if it is really 200 or 300 then you really need to get it down. Remember that the normal CYA test will report any CYA level over 100 as if it was 100.

    The Pool Calculator doesn't know what your current CYA level is or what your target CYA level should be, even though it starts with numbers in both of those columns. You need to enter a better idea of what your current CYA level is and you need to enter a target CYA level before what it tells you is meaningful. In your situation plausible target CYA level is around 90.
    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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