Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 8 of 8

Thread: Confused FC/CYA

  1. Back To Top    #1

    Join Date
    Aug 2013
    Location
    South Louisiana
    Posts
    41

    Confused FC/CYA

    In March of this year we had our first pool installed (18'x54" AGP). I have been on TFPC since installation and have been very happy. In late June or early July my water temp was consistently above 90 degrees and we had a low level algae bloom with CYA at 30 ppm and targeting 4 ppm FC. After a slam, I followed the advice of others on this site and increased to CYA of 40 ppm and targeted FC of 8 ppm with a minimum of 4 ppm. No problems, but I did have to go to 8.5 ppm FC every night to maintain a minimum of 4ppm FC because I get 12 to 13 hours of sun per day.

    This week, we had a small amount of green algae in the areas of the pool that has slower flow when the pump is on. I'm running the pump 9 hours per day on high and have a cartridge filter. The filter is clean. The kids have only been swimming about once per week because of school and extra curricula activities. I try to brush once per week, but got behind on it. I slammed and after two days I passed all criteria and was done. Today, I went to the pool store to kill time and they nearly dropped dead when I told them that my FC is brought up to 8.5 every night to maintain a minimum of 4. They suggested raising the CYA to 80 and getting back down to an FC of 3 or 4 ppm. I talked to a friend of mine who maintains pools and he was less concerned. He did feel that I should bring the CYA to 50 or 60 and so my FC will not swing so wildly. He feels that I should be targeting and FC of 5ppm and a minimum of 3 or 4 ppm.

    I'm usually adding 46 ounces of 8.25% bleach per night. I'm spending about $6 per week on bleach. Had to SLAM twice from March of this year to now. Am I adding to much chlorine and is my CYA too low?
    18'x54" Round AGP, 7,600 Gallons
    150 sq ft Cartridge Filter, 2-speed 2hp pump (Hard Plumbed)
    TFPC Method
    TF-100 Test Kit

  2. Back To Top    #2
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Location
    Columbia, SC
    Posts
    8,495

    Re: Confused FC/CYA

    Quote Originally Posted by Branch Fly View Post
    Today, I went to the pool store to kill time and they nearly dropped dead when I told them that my FC is brought up to 8.5 every night to maintain a minimum of 4. They suggested raising the CYA to 80 and getting back down to an FC of 3 or 4 ppm. I talked to a friend of mine who maintains pools and he was less concerned. He did feel that I should bring the CYA to 50 or 60 and so my FC will not swing so wildly. He feels that I should be targeting and FC of 5ppm and a minimum of 3 or 4 ppm.
    Ignore the pool store. They are giving you old stock information that is not based on the reality of the CYA/FC relationship.

    You friend is closer to reality. With the amount of sun you get your CYA should be at the top of the recommended range which is 50. With 50 CYA your target is six, minimum is 4.

    If you hqave areas of low circulation either you need to figure a way to improve it or brush those areas a little more regularly to get chlorine in the area.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

  3. Back To Top    #3
    pwrstrk's Avatar
    Join Date
    Aug 2012
    Location
    Elverson Pa.
    Posts
    4,758

    Confused FC/CYA

    I agree with Tim on everything except the target FC level , I'm going to suggest you target 7-8 and don't let it fall below 4. That gives you more wiggle room so you don't fall below your min of 4. Pool math would give you a target of 8 for a CYA of 50. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

  4. Back To Top    #4
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Location
    Columbia, SC
    Posts
    8,495

    Re: Confused FC/CYA

    Quote Originally Posted by pwrstrk View Post
    I agree with Tim on everything except the target FC level , I'm going to suggest you target 7-8 and don't let it fall below 4. That gives you more wiggle room so you don't fall below your min of 4. Pool math would give you a target of 8 for a CYA of 50. ��
    Well, we need to update the FC/CYA chart in the Pool School

    FC-CYA.JPG

    But, with all the sun I can agree a little more wiggle room would be nice.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

  5. Back To Top    #5
    pwrstrk's Avatar
    Join Date
    Aug 2012
    Location
    Elverson Pa.
    Posts
    4,758

    Confused FC/CYA

    I know. I personally feel 2 ppm isn't enough wiggle room. I never suggest that. I don't to it myself My CYA level is 40 and I target 7. Pool math gives the same target. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

  6. Back To Top    #6
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Location
    Columbia, SC
    Posts
    8,495

    Re: Confused FC/CYA

    Quote Originally Posted by pwrstrk View Post
    I know. I personally feel 2 ppm isn't enough wiggle room. I never suggest that. I don't to it myself My CYA level is 40 and I target 7. Pool math gives the same target. ��
    I know what you are saying, but I'm too new to deviate too much from published sources. I leave that to the senior folks...
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

  7. Back To Top    #7
    pwrstrk's Avatar
    Join Date
    Aug 2012
    Location
    Elverson Pa.
    Posts
    4,758

    Confused FC/CYA

    It can be brought up. It's the USA !!
    I look at it as it's playing it safe that way. I know people sometimes forget to bump FC levels up if the pool is getting heavy use and if you have a bunch of kids swimming like I have you know accidents are going to happen you have your butt covered with FC. Sometimes I can go a day if the weather is right and the pool sees little use, without having to add bleach. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

  8. Back To Top    #8
    Smykowski's Avatar
    Join Date
    Sep 2011
    Location
    Gurnee, IL (North Suburban Chi-town)
    Posts
    3,065

    Re: Confused FC/CYA

    Quote Originally Posted by pwrstrk View Post
    It can be brought up. It's the USA !!
    I look at it as it's playing it safe that way. I know people sometimes forget to bump FC levels up if the pool is getting heavy use and if you have a bunch of kids swimming like I have you know accidents are going to happen you have your butt covered with FC. Sometimes I can go a day if the weather is right and the pool sees little use, without having to add bleach. 😎
    ^^This^^

    I operate the exact same way. I run my CYA at 40 and keep my FC between 7 and 9 for all the reasons listed above.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

Posting Permissions

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