Become a TFP Supporter Pool Math Forum Rules Pool School
Page 1 of 2 12 LastLast
Results 1 to 20 of 38

Thread: Testing result I do not understand....

  1. Back To Top    #1

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Testing result I do not understand....

    Basically, CYA tested *higher* after a night of very significant rain (several inches) Other than salt, no other parameters were significantly changed. Salt decreased several hundred ppm (3300 to 2650) and CH went down from 280 to 250. Those changes all make sense to me which is why I tested this morning after the rains were over.

    What doesn't make sense is CYA tested higher by 15ppm. The inky explanation I can think of for that is operator error, although I've did the test the same way as always (it's subjective but not difficult to perform).

    Any thoughts?
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  2. Back To Top    #2
    pwrstrk's Avatar
    Join Date
    Aug 2012
    Location
    Elverson Pa.
    Posts
    4,758

    Re: Testing result I do not understand....

    I'm going to say testing error. I don't see how your CYA can read higher after a significant rain. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

  3. Back To Top    #3

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,077

    Re: Testing result I do not understand....

    CYA cannot go up unless you add more....it does not occur naturally.

    Margin of error on the test is plus or minus 10 ppm.

    Just curious why you performed CYA tests so close together...........3-4 times per swim season is generally often enough.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

    TFP Guide
    PAGirl's Avatar
    Join Date
    Jun 2012
    Location
    Central PA
    Posts
    2,388

    Re: Testing result I do not understand....

    Was it cloudier than it had been the last time you did the test? Brighter lighting?
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

  5. Back To Top    #5

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Quote Originally Posted by duraleigh View Post
    CYA cannot go up unless you add more....it does not occur naturally.

    Margin of error on the test is plus or minus 10 ppm.

    Just curious why you performed CYA tests so close together...........3-4 times per swim season is generally often enough.
    Just habit of doing all the tests, all the time. Learning, seeing what changes, what doesn't, etc. Generally figuring out the pool ....

    - - - Updated - - -

    Quote Originally Posted by PAGirl View Post
    Was it cloudier than it had been the last time you did the test? Brighter lighting?
    The pool water was/is the same, but the lighting conditions were certainly different. Overcast, no sun.
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  6. Back To Top    #6
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Testing result I do not understand....

    The lighting is critical to that test. Should be outside with bright indirect light. Overcast vs full sun could impact the reading.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  7. Back To Top    #7

    Join Date
    Jul 2014
    Location
    Peoria, IL
    Posts
    389

    Re: Testing result I do not understand....

    The cya is operator error. The other tests results seem off as well. That would take a significant water change/dilution to lower salt by 650ppm. According to pool math that is a 20% water change. How are you testing salt? Strips or Taylor K1766? The 1766 that I use is pretty much impossible to read wrong. The strips, not so.


    30x20 vinyl IG, Hayward SD60 with Pentair Dynamo 340219 2HP pump, Compupool CPSC24 SWG, Hayward H200FDN heater. APC automatic pool cover.
    Central Illinois

  8. Back To Top    #8

    Join Date
    Aug 2014
    Location
    Seminole, FL
    Posts
    92

    Re: Testing result I do not understand....

    The CYA test seems to cause newbies like me the most problem in getting a reasonably accurate measurement. I've had +/20ppm depending on light conditions and the person reading it. Peering over the top of the Taylor tube, I've even confused the shadow of my head with the black dot!!

    Been thinking about getting a CYA standard 50ppm sample, then putting the test tube on top of my AC plugged-in smartphone with a paint app that can vary the 'whiteness' of a full screen background to a known RGB in a dark room, and calibrating the RGB against the sample. Although I haven't got the sample yet, I do this already on my pool water and get consistent readings each time using the same 'white' background, assuming I'm not losing CYA over the last 3 weeks (haven't needed to backwash, drain & fill, or losing much to splash out)

    Any thoughts on this method?

    Mike
    Built 1980, 19' x 30' almost rectangular, screened 15,000 gal, plaster, Hayward DE 3620 filter (currently using cellulose), Emerson 1081 1HP pump, AquaCal Heatwave SuperQuiet SQ110R heater, Zodiac T5 Cleaner, Taylor K-2006 test kit

  9. Back To Top    #9

    TFP Guide

    chiefwej's Avatar
    Join Date
    Jun 2011
    Location
    Tucson
    Posts
    2,853

    Re: Testing result I do not understand....

    Turbidity can also effect your readings, but I would think you would notice if the water was cloudy enough to make a difference in the reading.

  10. Back To Top    #10

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Quote Originally Posted by bdex View Post
    The cya is operator error. The other tests results seem off as well. That would take a significant water change/dilution to lower salt by 650ppm. According to pool math that is a 20% water change. How are you testing salt? Strips or Taylor K1766? The 1766 that I use is pretty much impossible to read wrong. The strips, not so.


    Sent from my iPhone using Tapatalk
    I've been reading it from my SWCG. Even if it is off, it's the same device, so one would theorize consistently making the same error. Even if it isn't reading it entirely correct it's acting based on what it reads, so I have to make it happy to operate properly.

    I had thought about a good electronic tester for salt to reduce the error but those little electronic puppies cost a few hundred bucks and they seem to be horribly prone to calibration errors and disliked by postings here. I do not know about a Taylor K1766 and will look that up.

    We had torrential downpours for several hours and got several inches of rain. This was not a normal, insignificant rain event of a shower for an hour. Three days later, I still have standing water in the backyard and we're squishy and wet most everywhere.

    - - - Updated - - -

    Quote Originally Posted by chiefwej View Post
    Turbidity can also effect your readings, but I would think you would notice if the water was cloudy enough to make a difference in the reading.
    There's been no visible change in the cloudiness of the water. Can certainly understand where that would change the reading and will be alert for that in the future.
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  11. Back To Top    #11

    Join Date
    Jul 2014
    Location
    Peoria, IL
    Posts
    389

    Re: Testing result I do not understand....

    I feel your pain on the SWG having to be happy. They have a pretty large range that they will operate in and are by and large not that accurate. I would pick up that Taylor kit and then you should be able to recalibrate your cell based on that reading. That is what I did with my compupool and it has been about dead on ever since.
    The error in its number is likely because it is drawing water off of the skimmer (top) of the water. Which is much more heavily concentrated with rain than the bottom of the water or even more so deep end.

    Give the pump time to mix it up or swim in it and I bet it rebounds.


    30x20 vinyl IG, Hayward SD60 with Pentair Dynamo 340219 2HP pump, Compupool CPSC24 SWG, Hayward H200FDN heater. APC automatic pool cover.
    Central Illinois

  12. Back To Top    #12

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Quote Originally Posted by bdex View Post
    I feel your pain on the SWG having to be happy. They have a pretty large range that they will operate in and are by and large not that accurate. I would pick up that Taylor kit and then you should be able to recalibrate your cell based on that reading. That is what I did with my compupool and it has been about dead on ever since.
    The error in its number is likely because it is drawing water off of the skimmer (top) of the water. Which is much more heavily concentrated with rain than the bottom of the water or even more so deep end.

    Give the pump time to mix it up or swim in it and I bet it rebounds.


    Sent from my iPhone using Tapatalk
    Found K-1766 on amazon and already ordered it in on prime. Wouldn't the water draw be both from main drains and skimmers?

    I don't know of any way to recalibrate the salt cell. I asked Pentair about that when they visited my pool a few weeks ago and they indicated there was no way to recalibrate an InteliChlor. I'm sure there is within their factory production line, but interpreted that as not out in the field, being used.
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  13. Back To Top    #13

    Join Date
    Jul 2014
    Location
    Peoria, IL
    Posts
    389

    Testing result I do not understand....

    Looks like pentair changed that with the new ones. We had an older version and it was a breeze if you knew your salt level and how to do it. That sucks. And yes, some water would come from main drains and some from skimmer, but 50% rainwater and 50% 3200ppm saltwater will drag the number down. You may have to add a little salt, but if I had 20% refill rate rain my pool would overflow in a snap.

    Check NACL with the 1766 and report back.

    30x20 vinyl IG, Hayward SD60 with Pentair Dynamo 340219 2HP pump, Compupool CPSC24 SWG, Hayward H200FDN heater. APC automatic pool cover.
    Central Illinois

  14. Back To Top    #14

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Will do.

    Also, wanted to relate, that the salt cell, after 1 bag added, increased it's reading from 2650 to 3050, an increase of 400 ppm.

    Since one bag is stated to raise 10K gallons 500 ppm (i.e. 6 bags for 3000 ppm), one bag into 12K gallons should raise it slightly more than 400.

    Which is exactly the behavior I saw.
    Last edited by eqbob; 09-15-2014 at 07:36 PM. Reason: additonal info
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  15. Back To Top    #15

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Kit came in today. Salt cell reads 3200ppm. 1766 kit did 18 drops or 3600ppm.

  16. Back To Top    #16

    Join Date
    Oct 2013
    Location
    Chapin, SC
    Posts
    1,141

    Re: Testing result I do not understand....

    Both your cell and test kit can vary that much (+- 400)
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

  17. Back To Top    #17

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Quote Originally Posted by timerguy View Post
    Both your cell and test kit can vary that much (+- 400)
    Ok. Kewl. Didn't know that. The fact that they are in the same area tho' is good. Salt cell isn't way out of whack.
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

  18. Back To Top    #18

    Join Date
    Jul 2014
    Location
    Peoria, IL
    Posts
    389

    Re: Testing result I do not understand....

    You're good. All well within tolerance. Isn't that test as easy as it gets??


    30x20 vinyl IG, Hayward SD60 with Pentair Dynamo 340219 2HP pump, Compupool CPSC24 SWG, Hayward H200FDN heater. APC automatic pool cover.
    Central Illinois

  19. Back To Top    #19

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Yes. Quick and simple and clear results. Thanks for the recommendation. Good test to have in the stable.

  20. Back To Top    #20

    Join Date
    Jul 2012
    Location
    Central Texas
    Posts
    436

    Re: Testing result I do not understand....

    Anyone know what the number of the Taylor chlorine test kit is that does discrete numbers instead of ranges? I think in a previous thread it was called FAS/DPD test.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •