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

Thread: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

  1. Back To Top    #1

    Join Date
    May 2010
    Location
    New Orleans, LA
    Posts
    20

    Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    It came back today. Here are my readings

    FC - 8.0
    CYA - 60 (though I usually keep it closer to 75)
    TA - 70
    Salt - 3100
    pH - 7.5

    I don't understand why it keeps coming back. I run the pump on high 12 hours a day. The FC stays high. I haven't been running the SWG much because the FC has stayed double digits since the last shock.

    It is unusual the CYA dropped below 70 (probably because I added water to the pool 2 days ago with the FC at 11) and it has been very sunny since, but should that matter when the FC stays so high?
    15'x30'x54" oval AG; 12,500 gallons; Aquatrol SWG; Cartridge filter; 2-speed, 2-HP pump; 2 return jets

  2. Back To Top    #2

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    I have been having the same issue. Mustard Algae coming back after lots of scrubbing and shocking. I just got done with a four day Mustard Algae shock, no signs of any. I'm waiting to see what if anything grows. Like you, I was keeping my FC levels around 10 with a CYA of 60ish, and seemingly having no affect on the algae growth.
    17,000 Gallon plaster pool. Hayward Perflex EC65 DE Filter. 3/4 HP Hayward Superpump converted to dual speed. CircuPool RJ45. Skimmer, floor drain, two returns.

  3. Back To Top    #3
    Guest

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Have you shocked your pool at 18ppm and did an overnight chlorine test for loss? Have you cleaned your cartridge filter? what is your pool water temp?

  4. Back To Top    #4

    Join Date
    Dec 2009
    Location
    Central Massachusetts
    Posts
    2,690

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Quote Originally Posted by jparr
    Like you, I was keeping my FC levels around 10 with a CYA of 60ish, and seemingly having no affect on the algae growth.
    Mustard algea is tough to get rid of but enough chlorine will do the trick. At 60 ppm CYA, shock level for mustard is around 35 ppm. If it is mustard, you dont have near enough chlorine at 10 ppm to even touch it.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

  5. Back To Top    #5

    Join Date
    May 2010
    Location
    New Orleans, LA
    Posts
    20

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Quote Originally Posted by salp
    Have you shocked your pool at 18ppm and did an overnight chlorine test for loss? Have you cleaned your cartridge filter? what is your pool water temp?
    I shock it to at least 22-24 ppm, sometimes higher. I leave the SWG going to maintain FC levels while it's clearing. I clean the filter every 2-3 weeks (not since last algae about 2 weeks ago, though). Pool Temp has been around 85.
    15'x30'x54" oval AG; 12,500 gallons; Aquatrol SWG; Cartridge filter; 2-speed, 2-HP pump; 2 return jets

  6. Back To Top    #6
    Guest

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    bk406, hit it right on, if it is mustard algae, with what data you gave us, you need to shock around 35 - 38 ppm.

  7. Back To Top    #7

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Yellow/mustard algae is about twice as slow to kill as green algae so shock levels need to be higher. It also likes shade so can hang out behind light niches and under removable ladders. You need to put in poles and other equipment that would get back into the pool at some point after shocking. Also, keep the high shock level for at least an extra day beyond no visible algae, <= 1 ppm FC overnight drop and <= 0.5 ppm CC. If any of the algae survives, it can grow again unless the FC is kept at around 15% of the CYA level which can become impractical/expensive which is why it's better to completely kill it if possible.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  8. Back To Top    #8

    Join Date
    May 2010
    Location
    New Orleans, LA
    Posts
    20

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Quote Originally Posted by salp
    bk406, hit it right on, if it is mustard algae, with what data you gave us, you need to shock around 35 - 38 ppm.
    Are you answering me or jParr? Are you saying mine is likely mustard algae, too? The regular 24 ppm shock does seem to take care of it for the time anyway. Mine's not under shade or removable ladder necessarily. However, it does appear to begin in areas where the water doesn't circulate as well i.e. furthest from the return jets.
    15'x30'x54" oval AG; 12,500 gallons; Aquatrol SWG; Cartridge filter; 2-speed, 2-HP pump; 2 return jets

  9. Back To Top    #9
    benavidescj's Avatar
    Join Date
    Apr 2010
    Location
    Fleming Island, FL
    Posts
    431

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    dsharp, what does your algae look like? I do not see a CC or TC test result in your post. Have you done the overnight FC test? If not I recommend you do so and post those numbers so we can help you out. Without those numbers it is hard for us to determine if you have algae. It may look gone but the test may prove otherwise.
    Carlos
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

  10. Back To Top    #10
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    22,347

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    How are you testing?

    One thing bothered me in your initial post.
    I haven't been running the SWG much because the FC has stayed double digits since the last shock.
    When and what was your last shock?
    And, what's "not much" run time for the SWCG?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  11. Back To Top    #11

    Join Date
    May 2010
    Location
    New Orleans, LA
    Posts
    20

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Quote Originally Posted by Bama Rambler
    How are you testing?

    One thing bothered me in your initial post.
    I haven't been running the SWG much because the FC has stayed double digits since the last shock.
    When and what was your last shock?
    And, what's "not much" run time for the SWCG?
    I shocked about 2 weeks ago (last algae sighting) Since then the FC stayed so high I had the SWG off or, for the last couple of days, at 25% during the 12-hour pump run I give it each day. Normally, I run it around 40% to maintain. CC was 0 - 0.5. Overnight I lost 0-0.5 FC so I'm sure the algae was gone. If it comes back, I'll make better note of whether it was more yellow-ish. I hadn't considered that.

    My theory - One thing that may contribute is the two 50-lb sand bags in the pool that weigh down the steps are enclosed in giant "baggies" and there always appear to be algae INSIDE the baggies. I figured it was staying sealed in there, but it could be some gets out and feeds into the pool. Possible?
    15'x30'x54" oval AG; 12,500 gallons; Aquatrol SWG; Cartridge filter; 2-speed, 2-HP pump; 2 return jets

  12. Back To Top    #12
    benavidescj's Avatar
    Join Date
    Apr 2010
    Location
    Fleming Island, FL
    Posts
    431

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Repeating Dave's question, how are you testing?
    Carlos
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

  13. Back To Top    #13
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    22,347

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    You need to open those sand bags and get some chlorine in there. If algae got in algae can get out.

    If it were me I'd get rid of those bags and use 5 gallon buckets instead. Fill them with sand and water then add a pint of bleach to each and close them up tight.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  14. Back To Top    #14

    Join Date
    May 2010
    Location
    New Orleans, LA
    Posts
    20

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Quote Originally Posted by benavidescj
    Repeating Dave's question, how are you testing?
    I have the TFP test kit and test for FC and pH every day; CYA about once a week. TA every two weeks or so as that doesn't seem to fluctuate much. The SWG has an automatic readout for Salt level.
    15'x30'x54" oval AG; 12,500 gallons; Aquatrol SWG; Cartridge filter; 2-speed, 2-HP pump; 2 return jets

  15. Back To Top    #15

    Join Date
    Oct 2007
    Location
    Valrico, FL
    Posts
    536

    Re: Algae every 2 wks despite maintaining FC of 7+ in SWG pool

    Some types of organics love to hide. For example on my pool, they were hiding in the air piping of my spa jets!. Until I ran shock level water back through the air piping I was in the same boat.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

Posting Permissions

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