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Thread: CYA testing

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    CYA testing

    I just got a new refill of R-0013 from tftestkits I also got the 50 ppm standard so I could make sure I'm doing the test correctly. With the standard I couldn't ever get closer than 55 - and that only with holding it at chest level. The color of the ground makes a big difference too - I have three different color concretes and the lighter grey one got me the closest to 50 at 55 or so.

    Ok so I have an error of 5-10 maybe my eyes are going.

    So then I test my pool pulling a sample from as low as I could. 2 months ago I measured it at 60 or 80 and my mom and pop pool store that I trust measured it at 60. Today I measured it at 30 or lower??? How could I possibly have lost 30 ppm? Is it possible that the rest reagent is bad? I ordered the big bottle so I could do this test multiple times to calibrate my testing process. It arrived yesterday so it's not like it's been sitting around. Could it have been damaged in travel from excessive heat?

    I'm taking a sample to the pool store tomorrow but I'm stumped on this.
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Richard320's Avatar
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    Re: CYA testing

    I'd believe yourself, even reading off by 5 ppm, before I'd trust the pool store.
    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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    Re: CYA testing

    I'm shocking right now - can that affect the CYA test?
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Richard320's Avatar
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    Re: CYA testing

    Quote Originally Posted by carlscan26
    I'm shocking right now - can that affect the CYA test?
    I've never seen any reference to it the way I have with pH, but I think it's possible. I seem to recall my CYA reading changing depending on FC, but not by much.
    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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    Re: CYA testing

    Thanks Richard. I don't know what is going on. My FC usage is all over the place today too - looks like it's slowing down and then it picks back up again. Maybe it just isn't my day for testing lol.
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    With the standard I couldn't ever get closer than 55
    The accuracy of the CYA test is plus or minus 15ppm. With practice, you can usually home it in a little better but not much.

    Regardless, what you should look for is repeatability.......getting pretty close to the same thing on multiple testings.

    High FC or any other parameter out of normal has no affect on the test.

    The last place I would look for confirmation of accuracy would be a pool store....TRUST YOUR TEST RESULTS!

    The R-0013 reagent is inert and, to my remembrance, there has never been a report of it going "bad".
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: CYA testing

    Thanks Dave. Well that's good news then because I was reading the standard consistently at 60.

    On my real pool water test I am reading 30-40 so I'm puzzled as I measured it at 70 (60 with my +10 adjustment) just a month ago. I took a same to my mom and pop pool store who I do trust - they do the turbidity test and we've been within 10 of each other the other two times I measured against them. They're not a big chain store; I've discussed BBB with them and they got it except for the adding borates for water feel and pH stability and algae guard.

    Any ideas on how I lost half my CYA in 6 weeks? We have been using the pool almost daily for the last two weeks and about 3-4 for the month before that. I've topped off maybe a total of 4" most of which I think I lost to evaporation and not splash which we do have but nothing crazy. Or at least not in my mind; most of it is dripping off as we and the toys go in and out. Either way no where close to half my pool volume.

    I'll be watching consumption which has been about 1 qt per day for 2 ppm. If it goes up by much then I'll be bumping the CYA up to around 50.
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    Is there any chance your pool has a leak? One common way to lose CYA is a slow leak combined with an autofill system the hides the leak so you don't notice it.
    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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    Re: CYA testing

    No autofill. I don't think I have a leak based on how little I've had to fill it. I'll try the evaporation leak text to be sure.
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    If you don't have an autofill system, the amount of water you would need to replace to account for that much of a CYA drop would be very very obvious. You obviously don't have that kind of leak.
    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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    Re: CYA testing

    Yeah. Big mystery. Is it possible that the poop accident could have caused this? Some bacteria GE Erato g nitrogen killing the cya? The pool smells fine and I measure 0 CCs.

    I reran the test at 5:30 so not the brightest of light and I could still barely make out the dot with the tube filled to 30. It's definitely way down.

    I have grass upwind and about 20 feet from the pool. They used granular fertilizer a few weeks ago. I didn't see any on the deck around the pool though. But maybe?
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    So I'm done shocking. FC is currently 15 or was at 7:30 this morning. I have the LQ off to let the FC level drop today. Is it possible to calculate approximate CYA based on FC drop over x hours with full sun? Or are there too many other variables I'm not considering?
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    There are too many non-quantifiable things to get an accurate reading on that.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: CYA testing

    Doh!
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    Daytime FC loss can tell you if CYA is closer to 30 or closer to 80, but you can't get much more precision than that.
    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

  16. Back To Top    #16

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    Re: CYA testing

    Well I definitely know it's close to 30!
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    Quote Originally Posted by carlscan26
    I have grass upwind and about 20 feet from the pool. They used granular fertilizer a few weeks ago. I didn't see any on the deck around the pool though. But maybe?
    I wonder about this too. My friend's pool had 0 CYA and has been hit by granular fertilizer, from the pellet sized iron stains on the steps. That would be heavy nitrogen from urea probably, plus phosphates and potassium and then some iron and other minor metals in mix.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    Re: CYA testing

    So I said earlier that my CYA was close to 30 - I remeasured yesterday before adding CYA and filled it to the top so it was less than 30. So I added a gallon on liquid CYA (I didn't want to wait a week or have a sock hanging in the pool with how much use it's been getting and will get this weekend). Anyway so now today I'm reading it at 35. Consistently so I'm happy about that!

    Is the test more accurate at lower cya levels? It would seem to be given that the gradations spread out more as you go lower? Based on this assumption I'm going to adjust my offset down from +10 to maybe a 5. So I'm at 30 plus then the accuracy of the test puts me at 15-45?

    What do you guys recommend for a pool with full sun from 9 to 4 and partial until 6? Should I go for 40?
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
    Pentair VS 3050 pump, Quad DE 60 filter and SunTouch controller
    8 gallon Liquidator, Aquatherm EcoSun Solar Panels, 2 wheel ThePoolCleaner

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    Re: CYA testing

    What do you guys recommend for a pool with full sun from 9 to 4 and partial until 6? Should I go for 40?
    Knowing your location will help answer this. Where are you? City & State?
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    Re: CYA testing

    What do you guys recommend for a pool with full sun from 9 to 4 and partial until 6?
    What city and state are you in?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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