+ Reply to Thread
Page 6 of 6 FirstFirst ... 4 5 6
Results 51 to 57 of 57

Thread: CYA over 100 with yellow/mustard algae

  1. #51
    PoolDoc's Avatar
    PoolDoc is offline Administrator Quark Inspector PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars
    Join Date
    Jan 2005
    Location
    Georgia
    Posts
    11,386

    Default Re: CYA over 100 with yellow/mustard algae

    Richard - ChemGeek - uses PR10000 and reports that PR10000 *does* remove PO4 as predicted.

    But . . . what I'm seeing myself (I'm using it) suggests that it only does so AFTER you have lowered PO4 levels fully. What I suspect is that there are more phosphates in the pool system -- pipes, pool surface, filter media -- than there are in the water itself. This would not be surprising, since phosphates are often.added to water in the first place because of their abilities to attach to surfaces. If I'm right, then the attached phosphates will only be released back into the pool water when the PO4 levels begin to get low (< 500 ppb?).

    My guess is that attached phosphates will be low in all plastic pools with cartridge filters (plastic liner, plastic pipes, plastic equipment), but high in concrete or stone pools with sand filters.

    I would strongly encourage you, if you've reached 200 ppb, to go ahead and get that next quart. 200 ppb is NOT low enough to be very helpful, but it's very, very close to 100 ppb, which IS low enough. If you stop now, you are sort of like someone who started a 10k run, but stopped at 9.8k.

  2. #52
    PoolDoc's Avatar
    PoolDoc is offline Administrator Quark Inspector PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars PoolDoc 5 stars
    Join Date
    Jan 2005
    Location
    Georgia
    Posts
    11,386

    Default Re: CYA over 100 with yellow/mustard algae

    I should add, that I'm seeing a consistent MAJOR improvement in mustard algae control, when PO4 levels are at 150 ppb or less.

    By improvement, I mean that the mustard algae is MUCH slower growing, and MUCH less chlorine resistant.

  3. #53
    Join Date
    Jul 2013
    Location
    Northern Illinois
    Posts
    817

    Default Re: CYA over 100 with yellow/mustard algae

    How's it going?
    26K gal 20x40 rectangular IG vinyl pool; Apr 2014: New pump, liner, auto-cover, & water; Pentair Whisperflo 1HP pump; Pentair Trition sand filter; Cover/Star CS-500 auto cover; Taylor K-2006C; OTO

  4. #54
    Join Date
    Jul 2013
    Location
    North Texas
    Posts
    23

    Default Still battling this beast

    OP here with another update. Well, I still had the yellow algae all winter, despite maintaining FC in the 6-10 range with CYA around 30. I did buy a second pint of Orenda PR10000. I've now used all but about 3oz over the last several months, but phosphates are still hovering around 300-400ppb. Over the last 12 months, I've used 2 quarts of a Clorox product and now 2 pints of Orenda. According to the labels, this should have removed several thousand ppb. There is no phosphate in my source water and no other obvious source. I read PoolDoc's explanation of "attached" phosphate with much interest, so I'll keep trying.

    Another oddity, same as last year, my CYA mysteriously dropped like a rock to zero in the Spring. I've added some CYA to get back to about 30-40. I have a cartridge filter and don't lose much water normally, so I don't understand this loss of CYA. The pool was running all winter and water looked fine except for the recurring yellow algae.

    In any case, I'm now holding FC in the 10-15 range since April and sweeping several times each week. I'm also running the polaris about 3 hours per day instead of my normal 1 hour. So far, no yellow algae, but this could be because the polaris and I are sweeping it up every day. I'll cut back sweeping and see what happens this week. I'll also use the last 3oz of Orenda, but based on my experience, I'm quite certain that will have no effect on phosphates in the water.

    If any other suggestions, please let me know. Here are my numbers from this morning:

    FC=13.5
    CC=0
    pH=7.6
    TA=90
    CYA=35
    CH=280
    Borates=50
    PO4=400
    __________________________________________________
    35X20 in-ground gunite, free-form, 18k gal, pebbletec plaster, Pentair cartridge filter, Pentair 1.0 HP WhisperFlo pump, Polaris 280, heater, waterfall, Taylor K2006 kit and K1106

  5. #55
    chem geek is offline PF Supporter Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
    Join Date
    Nov 2004
    Location
    California
    Age
    64
    Posts
    2,226

    Default Re: Still battling this beast

    That's too bad that the Orenda product isn't cutting down the phosphates below 300 ppb. In my pool it got down to 100 ppb when it was used years ago. Since then, my phosphates have crept up to around 400 ppb (after around 4 years). I have 300-500 ppb phosphates in my fill water, but I use a pool cover so have minimal evaporation/refill from about 1 hour of pool use most days.

    As for CYA disappearing over the winter, that is possible if you let your pool go over the winter (i.e. if you don't continually disinfect it) where bacteria can consume CYA turning it into ammonia (which creates a HUGE chlorine demand upon opening) or to nitrogen gas (which doesn't have any chlorine demand). Sounds like you may have had the latter happen.

    With your low CYA you shouldn't need to keep the FC so high. Even to keep away yellow/mustard algae using chlorine alone that would take an FC that is around 15% of the CYA level instead of the more usual minimum for green/black algae prevention of 7.5%. At 35 ppm CYA, an FC of 5-6 ppm should prevent yellow/mustard algae growth if you have decent circulation in the pool. HOWEVER, this is at normal pool temperatures above 80ºF. In colder water, there is a lower active chlorine level so at 50ºF, for example, you'd need closer to 17 ppm to be equivalent (it might not be that extreme -- I'm using the CYA temperature dependence from Wojtowicz but those numbers may be off a bit). This seems consistent with what you've been seeing, though usually at colder temperatures the algae grows more slowly.

    Keep us posted with how it goes.
    15.5'x32' rectangle 16K gal IG concrete pool; 12.5% chlorinating liquid by hand; Jandy CL340 cartridge filter; Pentair Intelliflo VF pump; 8hrs; Taylor K-2006 and TFTestkits TF-100; utility water; summer: automatic; winter: automatic; ; PF:7.5

  6. #56
    Join Date
    Jul 2013
    Location
    North Texas
    Posts
    23

    Default

    Thanks chem geek. Regarding disappearing CYA, I thought that would only happen if you close the pool down and let it turn into a green sludge pond. I've never done that. As I noted in my prior post, mine was circulating all winter and was well chlorinated at all times. Under those conditions, is there any other mechanism that would consume CYA? The recurring yellow algae perhaps?

    I'll reduce the FC as you suggested, but at the first sign of the yellow beast, I'm taking it back up again. This is the lowest my CYA has been in a long time, so I want to take advantage of it and rid my pool of this hard-to-kill algae.

    Regarding phosphates, did you read what PoolDoc said in post #51 about "attached" phosphates? Do you agree? Should I just keep dosing with Orenda until I see a breakthrough below 300?

    Thanks,
    Mike
    __________________________________________________
    35X20 in-ground gunite, free-form, 18k gal, pebbletec plaster, Pentair cartridge filter, Pentair 1.0 HP WhisperFlo pump, Polaris 280, heater, waterfall, Taylor K2006 kit and K1106

  7. #57
    chem geek is offline PF Supporter Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
    Join Date
    Nov 2004
    Location
    California
    Age
    64
    Posts
    2,226

    Default Re: CYA over 100 with yellow/mustard algae

    I don't know why the CYA would disappear (other than water dilution from rain overflow) over the winter when it was disinfected. If the chlorine and pH levels were high, then the oxidation of CYA by chlorine is faster, but in cold water that shouldn't be very fast. In a pool during the summer the loss is usually around 3 ppm per month while in a hot spa it's around 5 ppm per month.

    I don't know what to do about the phosphates. It should get lowered more and maybe if they are released as PoolDoc says then doing another treatment might work, but I'd expect to see it drop soon after treatment and only slowly rise up if in fact the phosphates are "attached" elsewhere. If you had HEDP metal sequestrant in the pool, then chlorine oxidation of it will produce more orthophosphate -- do you have HEDP in the water?
    15.5'x32' rectangle 16K gal IG concrete pool; 12.5% chlorinating liquid by hand; Jandy CL340 cartridge filter; Pentair Intelliflo VF pump; 8hrs; Taylor K-2006 and TFTestkits TF-100; utility water; summer: automatic; winter: automatic; ; PF:7.5

+ Reply to Thread

Tags for this Thread

Bookmarks

Posting Permissions

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