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Thread: Never so happy to see FC falling!

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    Never so happy to see FC falling!

    Hello everyone,

    I've been posting in the "Got a bleach question" because my FC was sky high. Per your recommendations I went hunting for sodium thiosulfate. Yesterday I was able to get some from a service company (shoutout: THANKS VERY MUCH! Moonlight Pool & Spa in MD) who graciously gave me some because the pool store had none. I added it last evening.

    These were the readings from the last few days and what happened after adding the sodium thiosulfate:

    7/28 11am FC 85 and salt was 3800 (yikes) so we drained 10% and cleaned everything. We also re-measured the pool! SWG shut off. Using FAS-DPD. I had to put so much R-0871 reagent in the vial it never really got clear, just a light tan. Running low on reagent, gotta get some more!

    From 7/29 8am FC 65 CC 0 TA 210 CH 100 CYA 60 we only crept down to FC 35 by 8/2 at 2 pm (I checked twice a day)

    On 8/2 we also had pH 7.4 TA 230 CH 100? CYA 60 Salt 3200
    I added 8 oz HTH ph Minus to drop pH to 7.2 since TA was high, added 12 oz calcium carbonate and 3 oz plain cyanuric acid to bring CYA up to 75. I did not add any more salt since Intex instructions said 3000-3500 was okay.

    8/3 12pm FC 40 CC trace? pH 7.4 TA 180
    Then I added the sodium thiosulfate at 5 pm.

    I also realized I was making a mistake measuring CC, I wasn't adding R-0871 a second time after the R-0003 so I could have had some CC and never knew it. (pool filter was a darker green than lately, ugh!) I swore I read those instructions a hundred times!

    8/3 7pm FC 2 CC 2 doing the test right and it really turned clear, hooray! pH 7.2 TA 170 CH 120
    I turned the SWG back on and set it for 2 hours. I wanted to raise the FC to at least 20 because CC was over 0.5 so I added 1 regular jug bleach.

    8/4 8am FC 0.5 CC 0.5 (only one drop to clear)
    To get FC to 5 since CYA was 60+ I added 26 oz bleach.

    8/4 1pm FC 1.5 CC 0.5 (still one drop) pH 7.0 TA 150 CYA went down to 50 (hmm, shouldn't it go up?)

    I'm going to try to keep the FC at 5 and keep checking about every 6-8 hours to see what happens with CC over the weekend. I'm also going to keep SWG running right after sundown. Or should I choose another time?

    I'm leery of dumping too much more bleach in because I don't want the salt level to creep up, I don't want high TA and I don't really know what the SWG can do yet.

    I'm not crazy about the TA but it is dropping, but now my pH is down again! The PC says add 18 oz washing soda to bring pH back up to 7.5.

    Should I wait a few days to see if both pH and TA settle out a bit more before adding anything else? Especially since I'm trying to get a handle on the chlorine?

    I am finally feeling I have things somewhat under control, even if there is more work to do. I am grateful for all of the advice so far, and additional feedback is welcome.
    Intex 13' X 39" AGP, ~2800 gal filled, with Intex CS8110 SWG and Cu ion (now unplugged), Intex 635T pump/timer 1500 gph in a shady MD backyard.

  2. Back To Top    #2
    Richard320's Avatar
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    Re: Never so happy to see FC falling!

    Don't trust the pH test if the FC is above 10. Just wait.

    TA can be dealt with later, when everything else is under control and you're bored.
    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!

  3. Back To Top    #3

    Re: Never so happy to see FC falling!

    My CC is staying at 1 or less and the TA is dropping, but slowly. Readings lately:

    8/4 after 1 pm I added 24 oz bleach and at 7 pm the readings were FC 2 CC 1. SWG comes on around 7 pm each evening now for two hours.

    8/5 9 am FC 1.5 CC 0.5
    I wanted to try to get the FC up more than 5 so I added 48 oz bleach (the last half of a jug)

    8/5 2 pm FC 6 CC 0.5

    8/6 9 am FC 1 CC 1 pH 7.2 TA 140 CH 120 CYA 65
    I am going to add another 24 oz bleach and reset the SWG to run for 3 hours to see if FC will stay above 3 at least. It has only run three times so far.

    How high should I try to get the FC? With this CYA I need to be FC 4-5. I haven't gotten FC to stabilize yet but CC is 1 or less. Should I try to get 5-10? Should I run the SWG earlier in the day?

    I think the other numbers are looking good enough now I don't want to tinker with them any more!
    Intex 13' X 39" AGP, ~2800 gal filled, with Intex CS8110 SWG and Cu ion (now unplugged), Intex 635T pump/timer 1500 gph in a shady MD backyard.

  4. Back To Top    #4
    Richard320's Avatar
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    Re: Never so happy to see FC falling!

    I see FC 6 @ 2 pm. SWG on for 2 hours at 7 pm, and FC down to 1 at 9 AM. Something's consuming FC, and if CYA is 65, it probably isn't just the sun. There might still be something going on with the thiosulfate leftovers, or there might be algae. I have no clue what to tell you except to keep the FC level up or you will get algae.
    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!

  5. Back To Top    #5
    UnderWaterVanya's Avatar
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    Re: Never so happy to see FC falling!

    Quote Originally Posted by juniper55
    These were the readings from the last few days and what happened after adding the sodium thiosulfate:

    7/28 11am FC 85 SWG shut off. Using FAS-DPD.

    7/29 8am FC 65 CC 0

    8/2 2pm FC 35
    I added 8 oz HTH ph Minus to drop pH to 7.2 since TA was high, added 12 oz calcium carbonate and 3 oz plain cyanuric acid to bring CYA up to 75. I did not add any more salt since Intex instructions said 3000-3500 was okay.
    Did you turn the SWG back on?

    Quote Originally Posted by juniper55
    8/3 12pm FC 40 CC trace? pH 7.4 TA 180
    Then I added the sodium thiosulfate at 5 pm.
    How did FC go back up? How much sodium thiosulfate?

    Quote Originally Posted by juniper55
    I also realized I was making a mistake measuring CC, I wasn't adding R-0871 a second time after the R-0003 so I could have had some CC and never knew it. (pool filter was a darker green than lately, ugh!) I swore I read those instructions a hundred times!

    8/3 7pm FC 2 CC 2 doing the test right and it really turned clear, hooray! pH 7.2 TA 170 CH 120
    I turned the SWG back on and set it for 2 hours. I wanted to raise the FC to at least 20 because CC was over 0.5 so I added 1 regular jug bleach.

    8/4 8am FC 0.5 CC 0.5 (only one drop to clear)
    To get FC to 5 since CYA was 60+ I added 26 oz bleach.

    8/4 1pm FC 1.5 CC 0.5 (still one drop) pH 7.0 TA 150 CYA went down to 50 (hmm, shouldn't it go up?)

    I'm going to try to keep the FC at 5 and keep checking about every 6-8 hours to see what happens with CC over the weekend. I'm also going to keep SWG running right after sundown. Or should I choose another time?

    I'm leery of dumping too much more bleach in because I don't want the salt level to creep up, I don't want high TA and I don't really know what the SWG can do yet.

    I'm not crazy about the TA but it is dropping, but now my pH is down again! The PC says add 18 oz washing soda to bring pH back up to 7.5.

    Should I wait a few days to see if both pH and TA settle out a bit more before adding anything else? Especially since I'm trying to get a handle on the chlorine?

    I am finally feeling I have things somewhat under control, even if there is more work to do. I am grateful for all of the advice so far, and additional feedback is welcome.
    Simpler to keep the SWG off until you are completely done with shocking.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  6. Back To Top    #6

    Re: Never so happy to see FC falling!

    How long would the sodium thiosulfate linger?

    Should I try to get/maintain FC of about 4-5 since CC's staying at 1 or less or should I push up to 15-20 to shock?

    What is the best time of day to run a SWG?
    Intex 13' X 39" AGP, ~2800 gal filled, with Intex CS8110 SWG and Cu ion (now unplugged), Intex 635T pump/timer 1500 gph in a shady MD backyard.

  7. Back To Top    #7
    frogabog's Avatar
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    Re: Never so happy to see FC falling!

    If CC is 1ppm, ever... it's too high. CC at .5ppm is ok, but 1ppm CC is not. Losing 1ppm FC overnight (OCLT) is ok, but not more than 1ppm.

    So that would mean bringing the water to shock level, then maintaining it with testing and re-dosing. Do not run the SWG while shocking, it will skew your results. Maintain shock level throughout the process, letting it drop below shock level will backstep you.

    You can run the SWG whenever you like, but keep in mind that even with a SWG you've got to make sure enough chlorine is produced before the end of the day to be above minimum. Depending on when you run the SWG, ending the day at minimum could be a problem however. If the SWG runs during the day, it's got to turn on before the water falls below minimum. So if you end the day at 3ppm, that SWG better start producing chlorine a couple hours before the sun hits the poo0,l or people get in. If you lose 1ppm overnight however (which could be normal) then it's below minimum already before it even starts up. This is why I prefer not to actually see minimum when testing... ever. And especially not at the end of the day when SWG is all done.

    I'm working with a modified BBB/SWG schedule and am still fairly new to SWG but I'm going with the concept that the SWG is no different than adding bleach every day, except I don't actually add it. So with that in mind, I am running SWG during the day in the hopes of finishing the day at 7ppm. Worst case scenerio then would be that the next day the SWG doesn't make enough chlorine to be at 7ppm after dark but the water still remains above minimum (even if the SWG made nothing assuming 50% loss).

    I think I'm getting there, but I did boost the FC twice this weekend with bleach to get back up to 7ppm at night (it was ending the day at 4-5ppm, I didn't much care for that). I'm hoping the boost took and that automatic run times keep it there. Getting dialed in with this hourly SWG from Intex is not exactly easy.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

  8. Back To Top    #8

    Re: Never so happy to see FC falling!

    Well I am slowly getting the FC to rise and my CC this morning was only 0.5 again. I'm going to turn the SWG back off and add enough bleach to try to get the FC up to shock level, esp. since we're going on vacation for a few days. We finally got rain this morning, an hour's worth so I expect some algae formation with that.
    Intex 13' X 39" AGP, ~2800 gal filled, with Intex CS8110 SWG and Cu ion (now unplugged), Intex 635T pump/timer 1500 gph in a shady MD backyard.

  9. Back To Top    #9
    UnderWaterVanya's Avatar
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    Re: Never so happy to see FC falling!

    Quote Originally Posted by juniper55
    Well I am slowly getting the FC to rise and my CC this morning was only 0.5 again. I'm going to turn the SWG back off and add enough bleach to try to get the FC up to shock level, esp. since we're going on vacation for a few days. We finally got rain this morning, an hour's worth so I expect some algae formation with that.
    If you are going to go on vacation - then by all means leave the SWG on while away. Even if it isn't keeping up - it's better than zero added chlorine.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  10. Back To Top    #10

    Re: Never so happy to see FC falling!

    Wow, I just checked my pool an hour ago. We added one jug of bleach before leaving last Thursday and let the SWG run for 4 hours/day.

    Today's reading (Sunday) we had FC of 12, a little high, and CC less than 0.5. Barely one drop of R-0871! Clear water, just debris because it hasn't been vacuumed in a week and we got more rain again.

    I am SOOOOO glad I found this site and am SOOOOO glad for those Taylor test kits! I'll dial back the SWG an hour and see how that affects things. Thank you to everyone for the great advice, I am loving this website!
    Intex 13' X 39" AGP, ~2800 gal filled, with Intex CS8110 SWG and Cu ion (now unplugged), Intex 635T pump/timer 1500 gph in a shady MD backyard.

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