Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 15 of 15

Thread: Opinion on what seems like an overnight FC loss

  1. Back To Top    #1
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Opinion on what seems like an overnight FC loss

    Got new liner and pool fill on June 5th.
    Brought FC to 12ppm for 2 days(June 6th and 7th), passed OCLT.
    Let drift the FC for a few days.
    Added CYA to bring to about 40.

    Here are the readings since then:
    date FC pH TA CH CYA SALT SWCG TempH2O addition/action
    9 juin 10 8 175 500 2600 off 62 16oz MA
    10 juin 8.5 7.6 150 500 35 off 63 16oz MA + 28 lbs salt
    11 juin 6.5 7.5 140 3200 off 64 16oz MA
    12 juin am 6 7.4 1 64 Turn on SWCG
    12 juin pm 5 7.5 120 2 74 16oz MA
    13 juin am 5 7.3 110 35 2 74
    13 juin pm 5 7.4 2 80 added 16oz CYA
    14 juin am 5 7.4 2 77
    14 juin pm 5.5 7.5 2 80 Clean filter
    15 juin am 6 7.6 1 77 16oz MA
    15 juin pm 5.5 7.3 1 77
    16 juin pm 5.5 7.4 100 1 75
    17 juin pm 5.5 7.6 100 1 75 16oz MA
    18 juin pm 5.5 7.4 90 40 1 75
    19 juin pm 5 7.6 1 75 16oz MA
    20 juin pm 5 7.3 80 500 1 75
    21 juin pm 5 7.4 1 76
    22 juin pm 2.5 7.5 2 76 16oz 10% bleach(brought FC to 5)
    23 juin am 3 7.6 80 35 3000 4 76 brought SWCG to 4
    23 juin pm 4 7.6 4 77 8oz MA
    24 juin am 3 7.4 4 77 8oz 10% bleach
    24 juin pm 5 7.5 70 4 77
    25 juin am 3 4 77

    (am = 6am, pm = 4:30pm)
    pump is at full speed from 6am to 5pm, then slow speed 5pm to 6am.
    SWCG is not generating chlorine at low speed (low flow LED on)
    Actions are taken after the reading.

    Now, here is my concern:
    - I seem to start losing FC overnight (~2ppm), but maybe I need to test later (around 9:30 instead of 4:30).
    - What's odd to me is that from june 12th to june 21th, with SWCG set to lowest setting, I would stay at 5/5.5 PPM. And on June 22nd, I dropped at 2.5
    - Water is crystal clear and has been since a few days after the fill.

    Should I be concerned about that?
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  2. Back To Top    #2

    Join Date
    Jun 2011
    Location
    Long Beach, CA
    Posts
    2,669

    Re: Opinion on what seems like an overnight FC loss

    If I'm reading your chart correctly, you are at level 4 for the SWG output % and with 11 hours of pump time that turns on the SWG, I get that you are adding 2.38ppm of chlorine a day. You should bump up the CYA to 60 for now and see how that works out. I don't see anything wrong with the SWG with those settings.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

  3. Back To Top    #3
    DaninFLA's Avatar
    Join Date
    Apr 2015
    Location
    Sarasota, FL
    Posts
    1,011

    Re: Opinion on what seems like an overnight FC loss

    you need to do your OCLT after sunset and retest before sunrise. while you are doing the OCLT, your SWCG needs to be off. Also, raise your FC up before the OCLT to maybe 10-15 for the test.

    also, you are running your pump a lot more than needed. I have a SWCG, with a pool in full sun in Florida and I run my pump a total of 5 hours. doesn't hurt anything, just trying to save you some $$
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

  4. Back To Top    #4


    TFP Guide

    cowboycasey's Avatar
    Join Date
    Jul 2013
    Location
    Fletcher, OK
    Posts
    3,346

    Re: Opinion on what seems like an overnight FC loss

    +1, bring your CYA to 70 or 80 and you should be able to run your pump and SWG about 6 hours and be good
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
    links: pool school * Recommended-Levels * SLAM * CYA chart * Test kits * How To Post Pictures * Poolmath * OCLT ** Support your website if we helped you :) **

  5. Back To Top    #5
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    Will do another properly done OCLT.
    Reason behind the fairly long high speed pump run time is because I have many trees, and skimmer will capture better at high speed compare to low speed.
    My CYA was kept low, since I had my SWCG set to minimum(1) and FC would stay at 5. Because of that I didn't want to raise it more and end up with too much FC.
    Now, that I set SWCG to 4, I could raise my CYA. But, will do my overnight test 1st in case SLAM is needed.
    But, I'm very puzzled at the steady state of the pool, to the sudden use of FC.
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  6. Back To Top    #6
    DaninFLA's Avatar
    Join Date
    Apr 2015
    Location
    Sarasota, FL
    Posts
    1,011

    Re: Opinion on what seems like an overnight FC loss

    gotcha on the high speed setting to skim. I would personally just run it at that then for the amount of time needed to properly skim/clean your pool.

    remember, the SWCG can be changed by setting and duration. I.e. if you run it at 10% for 24 hrs, you will get the same amount of chlorine running it for 20% for 12 hours, or 40% for 6 hours and so on. so you have the ability to change as well.

    also, your SWCG should be running while your pump is on the low setting...
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

  7. Back To Top    #7
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    SWCG has its low flow LED on when pump is on low, and won't generate Chlorine because of that.

    I just went out and decided to look at the filter, and it was very dirty with pollen and insects. So, I clean it very well and replaced my pressure gage that was not working. This will help me monitor the cleanliness of the filter. It had been clean 15 days ago, so was assuming it would be good (without a working gage I couldn't tell until opening it).

    Maybe, my filter was consuming the FC from being too dirty. Could that be it?
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  8. Back To Top    #8
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    Quote Originally Posted by ping View Post
    If I'm reading your chart correctly, you are at level 4 for the SWG output % and with 11 hours of pump time that turns on the SWG, I get that you are adding 2.38ppm of chlorine a day.
    Out of curiosity, how did you get to the 2.38ppm of chlorine a day?
    Do you have a formula somewhere?
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  9. Back To Top    #9

    Join Date
    Jun 2011
    Location
    Long Beach, CA
    Posts
    2,669

    Re: Opinion on what seems like an overnight FC loss

    Your SWG is capable of generating 0.98lbs of chlorine a day and converting those numbers by how many hours you run the pump and the SWG output % I calculated that you were potentially adding 2.87 ounces of chlorine gas to the pool a day. I then entered that number into effects of chemicals in PoolMath and it calculates out to be 2.38ppm of chlorine in your pool.

    There are other formulas that can be used to calculate out but the main numbers that you need are the maximum production in 24 hours which is .98lbs or 15.68 ounces, the SWG on time, and the SWG output %.

    - - - Updated - - -

    Your SWG is capable of generating 0.98lbs of chlorine a day and converting those numbers by how many hours you run the pump and the SWG output % I calculated that you were potentially adding 2.87 ounces of chlorine gas to the pool a day. I then entered that number into effects of chemicals in PoolMath and it calculates out to be 2.38ppm of chlorine in your pool.

    There are other formulas that can be used to calculate out but the main numbers that you need are the maximum production in 24 hours which is .98lbs or 15.68 ounces, the SWG on time, and the SWG output %.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

  10. Back To Top    #10
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    So, I did OCLT, but forgot to raise FC.

    June 25th, 9:15pm: FC: 5.2, CC: 0
    June 26th, 5:50am: FC: 4.6, CC: 0

    It seems like my dirty filter was likely eating my FC.
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  11. Back To Top    #11
    DaninFLA's Avatar
    Join Date
    Apr 2015
    Location
    Sarasota, FL
    Posts
    1,011

    Re: Opinion on what seems like an overnight FC loss

    Quote Originally Posted by jorivesud View Post
    So, I did OCLT, but forgot to raise FC.

    June 25th, 9:15pm: FC: 5.2, CC: 0
    June 26th, 5:50am: FC: 4.6, CC: 0

    It seems like my dirty filter was likely eating my FC.
    you need to redo it with a high FC, will magnify any decreases. you had 0.6ppm...wouldnt be surprised if that's over 1ppm when you raise it to 15ppm and redo. for example, you had a 0.6ppm loss from 5.2...that's a 11.5% decrease in FC. if you raise it to 15ppm, a 1ppm drop would be 6.6% decrease in FC. so you are double. But its not really a linear relationship...so retest with high FC and report back.

    dirty filters aren't eating FC anymore than algae in your pool, its all in contact with the same water/FC
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

  12. Back To Top    #12
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    Location
    DFW, TX
    Posts
    23,994

    Re: Opinion on what seems like an overnight FC loss

    Agreed, OCLT should be done with at least 10 ppm FC.

    Usually when a filter gets that dirty that fast it is because of algae starting to grow in the pool.

    Here are the early signs of algae growth:
    1 higher than normal chlorine consumption, gets a little worse every day
    2 filter getting dirtier much faster than normal
    3 slightly slimy pool walls or small 1/4" patches of algae, gets worse every day
    4 slightly cloudy water, gets a little worse every day
    5 water starts to turn green
    6 frogs and salamanders move in and it is officially a pond!

    With an SWG this can be a fairly slow process over one to several weeks. You don't always get all symptoms but any one or two of them is your early sign to manage your pool a little more closely and probably keep a little more chlorine in the pool.
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    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

  13. Back To Top    #13
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    Ok, as per recommendation, I did an OCLT at higher FC.
    - brought my FC to 15 at 9:15pm yesterday. (Might as well bring it to shock and be ready if SLAM was needed)
    - brushed the pool thoroughly.
    - this morning at 5:30am, it was at 14
    - SWCG started at 6am, at 9am I was back at FC = 15
    - I will leave it like this and do another OCLT tonight.

    A drop of 1 is enough to think I could have something growing?
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  14. Back To Top    #14
    jorivesud's Avatar
    Join Date
    Jun 2015
    Location
    Ottawa, Canada
    Posts
    58

    Re: Opinion on what seems like an overnight FC loss

    Last OCLT results:

    Sunday night 9pm, FC: 14.5
    Monday morning 6am, FC: 14.5

    I guess I had something that was just about to start, and seems like it got tackled on time and could be killed quickly.
    I will now let my FC drift to regular level.

    Thanks for not letting me ignore it.
    12x20 vinyl liner + fiberglass steps. (6800 Gallons)
    SWCG - Hayward Salt&Swim 3C
    Hayward XStream Cartridge Filter (200 SQ.FT)
    Hayward TriStar VSP
    Raypak heat pump, Taylor K-2006 test kit.

  15. Back To Top    #15
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,934

    Re: Opinion on what seems like an overnight FC loss

    It's a good feeling when you know you've done it. Enjoy.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

Posting Permissions

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