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Thread: FC not dropping?

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    FC not dropping?

    OK so now that i have drained and refilled my tub to get rid of cc and start new without any additives like spa marvel. My FC is not dropping much at all.


    raised the FC last night after soak to 8ppm. 24 hours later it was about 3ppm. So dropped 5ppm


    added 1.5 oz to bring it up to 6ppm

    about 40 min later 3 of us soaked for 40-50min. checked the FC level and it was still 5 ppm.

    Does that make sense? I thought you needed roughly 2 - 2.5 oz of 10.5% chlorine per person per hour. So should 3 of us for ~50 min not added enough waste to cause the FC level to drop more than 1 ppm?


    I mean if it is only using that much, that is good, just going against what i thought i understood. I told my kids that after they use the hot tub throw in 2 oz chlorine per person. They don't know how to test and everything.

    But based on what i'm seeing that would be way too much
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  2. Back To Top    #2

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    Re: FC not dropping?

    Depends on whether you're going to be in the spot every day. I find that with the two of us using it every day or two, 2 ounces after every use work just about perfect.


    Sent from my iPhone using Tapatalk
    15000 gal in-ground rectangular concrete/pebble-tech pool. Hot Springs Prodigy 325 gal spa.

  3. Back To Top    #3

    Re: FC not dropping?

    I'm still new to this but what I'm seeing with my 370 gallon tub is the free chlorine starts to drop about 2 hours after bathers exit.

    Without my knowledge, my wife and 2 kids used the tub the other night b4 soaking the tub was at 5pm FC. They soaked for 45 minutes and they tested after getting out, FC was 4ppm (they rinse off b4 entry and are very new to this water testing thing). Based on the 4 ppm reading they didn't add any chlorine even though I've told them to add 2 oz for each adult, 1 oz for my 8 yr old after each soak.

    When I got home from work the next day at 530pm, I tested the tub, zero FC which baffled me; I took FC to 17 ppm and pulled the pillows. Three hours later it was 13.5 ppm, at 11pm it was at 9.5ppm so I took it back up to 15ppm. This morning it was at 9ppm, put it back to 15ppm and 8 hours later it's sitting at 11ppm.

    Like I said, I'm still dialing this tub in but I'm finding 2 oz of 12% chlorine per person seems to give me enough reserve until I test the next day.

    I'd rather have a little too much than too little chlorine in the tub since it oxidizes fairly quickly with regular use - my recommendation to them was after a soak - add 2 oz of chlorine.

  4. Back To Top    #4

    Re: FC not dropping?

    Quote Originally Posted by twodogs02 View Post
    I'm still new to this but what I'm seeing with my 370 gallon tub is the free chlorine starts to drop about 2 hours after bathers exit.

    Without my knowledge, my wife and 2 kids used the tub the other night b4 soaking the tub was at 5pm FC. They soaked for 45 minutes and they tested after getting out, FC was 4ppm (they rinse off b4 entry and are very new to this water testing thing). Based on the 4 ppm reading they didn't add any chlorine even though I've told them to add 2 oz for each adult, 1 oz for my 8 yr old after each soak.

    When I got home from work the next day at 530pm, I tested the tub, zero FC which baffled me; I took FC to 17 ppm and pulled the pillows. Three hours later it was 13.5 ppm, at 11pm it was at 9.5ppm so I took it back up to 15ppm. This morning it was at 9ppm, put it back to 15ppm and 8 hours later it's sitting at 11ppm.

    Like I said, I'm still dialing this tub in but I'm finding 2 oz of 12% chlorine per person seems to give me enough reserve until I test the next day.

    I'd rather have a little too much than too little chlorine in the tub since it oxidizes fairly quickly with regular use - my recommendation to them was after a soak - add 2 oz of chlorine.


    So curious, what would your normal drop in FC be in 24 hour period?

    I'm finding i don't have to add the 2oz per adult, which is what triggered this post.

    we use the tub almost daily and usually min of 3 people in, sometimes as much as 6.

    I bring up to 8ppm and find it is still around 3ppm the next day. Soak, test after getting out and usually has not dropped much, add enough to bring back up to 8ppm.


    Maybe i'm testing too soon after getting out? But i'm finding there is still chlorine in 24 hours later. usually after we get out, its off to bed, so don't want to stay up go back outside 2 hours later.
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  5. Back To Top    #5

    Re: FC not dropping?

    I'm hoping I can answer that question in another few days. Your and my goal seem to be the same - determine average drop of FC over 24 hours.

    I'll post my results in a few days once I get out of these higher levels of FC.

    I keep my tub at a constant 102, what's yours at, how many gallons? Except for me, it's all female bathers with long, thick hair.

  6. Back To Top    #6

    Re: FC not dropping?

    Quote Originally Posted by twodogs02 View Post
    I'm hoping I can answer that question in another few days. Your and my goal seem to be the same - determine average drop of FC over 24 hours.

    I'll post my results in a few days once I get out of these higher levels of FC.

    I keep my tub at a constant 102, what's yours at, how many gallons? Except for me, it's all female bathers with long, thick hair.
    I keep my tub at 101, it is roughly 475 gallons.

    Last night 3 of us (my wife, stepson and I) had a soak. I tested after we got out FC was 3.5, so i added 1.5 oz which should have brought it close to 8ppm.

    I will retest tonight, before i get in to see how much it dropped. I'm going to guess it is between 2 and 3.5ppm

    I'm a bit surprised at how little chlorine it seems to be using. We must be really clean folks
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  7. Back To Top    #7

    Re: FC not dropping?

    Quote Originally Posted by outdoor View Post
    I keep my tub at 101, it is roughly 475 gallons.

    Last night 3 of us (my wife, stepson and I) had a soak. I tested after we got out FC was 3.5, so i added 1.5 oz which should have brought it close to 8ppm.

    I will retest tonight, before i get in to see how much it dropped. I'm going to guess it is between 2 and 3.5ppm

    I'm a bit surprised at how little chlorine it seems to be using. We must be really clean folks


    So tested and FC is 3.5ppm.
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  8. Back To Top    #8

    Re: FC not dropping?

    Quote Originally Posted by outdoor View Post
    So tested and FC is 3.5ppm.
    So since last weekend when i drained, cleaned and refilled my tub, the water has been much clearer and Chlorine loss seems to be low.

    As well my cc chlorine issue i was having is gone, obviously.

    So i've tested daily, sometimes twice or 3 times. before soak, after soak, in the morning.

    and at no time did i not have chlorine.

    Well my last few tests show perhaps just a hint of cc maybe .5 or less. since when i add the 5 drops it is not perfectly clear.

    Why would this be?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  9. Back To Top    #9
    JoyfulNoise's Avatar
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    Re: FC not dropping?

    Is the tub closed? If so, add some bleach to increase your FC a bit and then leave the tub open on recirculate mode. Do this for about an hour and then see where your FC/CC is at. CCs are volitile chemical compounds and easily outgas from the water if the tub is open to air. If you can get some sunshine on it too that will help.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  10. Back To Top    #10

    Re: FC not dropping?

    Quote Originally Posted by JoyfulNoise View Post
    Is the tub closed? If so, add some bleach to increase your FC a bit and then leave the tub open on recirculate mode. Do this for about an hour and then see where your FC/CC is at. CCs are volitile chemical compounds and easily outgas from the water if the tub is open to air. If you can get some sunshine on it too that will help.
    Yes tub was closed

    I'm surprised that after 1 week cc can start to form?

    OK so i brought FC up to 12ppm and running open with all jets and air on for 20min pump cycle then leave open for another 40 min

    it is raining and cloudy out, so not sure if any sunlight will assist. The color is so faint for cc I'm guessing it is .2 or below, so you would think (or hope) that 12ppm and 1 hour exposed should do the trick

    now my FC will be a bit high tonight for use
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  11. Back To Top    #11
    JoyfulNoise's Avatar
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    Re: FC not dropping?

    Do you know what your CYA level is yet?
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  12. Back To Top    #12

    Re: FC not dropping?

    Quote Originally Posted by JoyfulNoise View Post
    Do you know what your CYA level is yet?
    about 30ppm


    As well my ph seems between 7.8 and 8.2 and TA is 50. Should i lower pH with acid and try and raise TA back to 50/60 or will that just in turn raise pH again?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  13. Back To Top    #13

    Re: FC not dropping?

    Now that the chlorine levels have come down, here is my FC drop:

    Measured this morning at 0545 FC=3.0

    Just measured again at 1645, FC= 1.5

    No use through the day, added 1.5 ounces of 12.5% chlorine, temp at 102, PH 7.4, TA 55, CYA 40

  14. Back To Top    #14
    Mod Squad pooldv's Avatar
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    Re: FC not dropping?

    Quote Originally Posted by outdoor View Post
    about 30ppm


    As well my ph seems between 7.8 and 8.2 and TA is 50. Should i lower pH with acid and try and raise TA back to 50/60 or will that just in turn raise pH again?
    Yes, lower ph to 7.6 and raise PH back to 50 if needed.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: FC not dropping?

    Outdoor, did you just drain/refill or did you run something through to clean it first (Ahh some?)

    I'm looking at the same thing I think. FC is dropping from 6ppm to 1ppm in 24h or less (no use) and CC is at 1ppm. Can't seem to drop that at all and I want to get this figured out before it starts getting too around here.

  16. Back To Top    #16

    Re: FC not dropping?

    Quote Originally Posted by bikeguy View Post
    Outdoor, did you just drain/refill or did you run something through to clean it first (Ahh some?)

    I'm looking at the same thing I think. FC is dropping from 6ppm to 1ppm in 24h or less (no use) and CC is at 1ppm. Can't seem to drop that at all and I want to get this figured out before it starts getting too around here.
    Yes, I used Ah-some. It seems to work very well. I just received my brand new tub around Sept 1st and though it was only 5 weeks old from Factory at most i got quite a bit of gunk

    see video

    Ahh-Some Hot Tub Cleaner WORKS!.mp4 - YouTube
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

  17. Back To Top    #17

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    Re: FC not dropping?

    Thanks. I recieved mine around Oct 6th ish as well. Same store I'm guessing as yours is an Artesian as well.

    I've just been hammering it with chlorine and (keeping it around 12ppm) trying to see if I can get it to keep a level of FC. Not sure what's going on, right now its dropping ~50% of the FC level in 12h or so (if I can believe my colorQ kit).

    I think you said after you refilled it (after Ahh some) the chlorine demand dropped as well?

    Very frustrated right now. I've order a test kit but its at the border and I can't get it for a week or two unfortunately. I've tried several stores for a water test and they're all over the map and the stores seem to use everything from strips to test the water to the Lamontte spin tester (can't remember the name) but I don't really believe any of the results as they don't make a lot of sense.

    Where did you get your Ahh-some? mail order I guess.

    450 US Gallon (1703L) Artesian Grand Bahama Hot Tub
    Chlorine + Nature 2 (for now)
    ColorQ Pro 7 and TF-100

  18. Back To Top    #18
    JoyfulNoise's Avatar
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    Re: FC not dropping?

    If biofilms are present, then shocking makes no difference. It has been shown in peer-reviewed studies that chlorine can not penetrate the biofilms deep enough to kill anything that is actively growing and those studies used very high chlorine levels with no CYA, conditions not found in any typical pool or spa. So if your tub is new, you definitely should use a spa cleaner. The plumbing will have oily residues in it from the manufacturing process and the stagnant water left behind from pressure testing will almost certainly have created a moist enough environment to allow bacterial films to grow.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  19. Back To Top    #19

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    Re: FC not dropping?

    Thanks for the response. I decided tonight that I just need to bite the bullet and do a purge/clean. I have the Ahh Some ordered tonight so it should be here early next week and I'll do the clean next weekend.

    Not having used Ahh some before will I need to replace the filters or can they just be cleaned? Is there any danger in running the tub for a while without the filters provided I've taken out any particulate matter that I can see? How about the pillows? I guess these should be pulled as well. Outdoor I saw that you pulled your pillows at the end. What did you do with your filters?

    Thanks - Shawn

    450 US Gallon (1703L) Artesian Grand Bahama Hot Tub
    Chlorine + Nature 2 (for now)
    ColorQ Pro 7 and TF-100

  20. Back To Top    #20
    JoyfulNoise's Avatar
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    Re: FC not dropping?

    If you go to the website they have instructional videos. You can pull the filter(s) out and float them in the tub full of Ahh-some while it runs. That will clean the filters as well.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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