Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 5 of 5

Thread: Where should CYA be with a SWG?

  1. Back To Top    #1

    Where should CYA be with a SWG?

    I have a SWG (IC-20) and my CYA is around 35. The pool store and builder say this is fine. But Pentair says it should be much higher...in the 60-80 range.

    Should I increase this? I notice over the last week or so my FC has been dropping and I've been having to increase the output on the SWG.

  2. Back To Top    #2

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,083

    Re: Where should CYA be with a SWG?

    Welcome to the forum Yes, you should increase your CYA to around 60-80ppm. You can find suggested levels for all your chemistry in Pool School in the upper right hand corner.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

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

    Re: Where should CYA be with a SWG?

    Welcome to TFP!

    The higher CYA level is needed if the pool is exposed to sunlight. If it is an indoor pool or is always shaded, then the CYA need not be as high. Dave assumed your pool was an outdoor pool exposed to sunlight, and most likely that is the case. I just wanted to let you know more specifics if this is not the case.
    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"

  4. Back To Top    #4
    susa's Avatar
    Join Date
    Oct 2010
    Location
    Deep South
    Posts
    578

    Re: Where should CYA be with a SWG?

    While the recommendations you've received are quite valid, a contrasting point-of-view is that when I maintained for the first 12 months CYA at around 70, with IC-40 running at about 20% and runtimes at around 8 to 10 hours per day, small amounts of black spot algae would develop unless brushed every other day and FC stayed at around 4 to 5.0 each day. When I allowed CYA to drop to around 20, the same runtime, same FC levels(also same pH, TA, CH), the black spot algae disappeared

  5. Back To Top    #5

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

    Re: Where should CYA be with a SWG?

    The recommendations assume good circulation, non-pitted pool surfaces, and elimination of nascent algae prior to maintenance levels. If one has a pool that has existing black algae growing in deeper pits or yellow/mustard algae behind light niches or has areas of poor water circulation, then a higher FC/CYA ratio would be needed to prevent algae growth. That can be accomplished through a higher FC or a lower CYA, but doing the latter would usually require the SWG to be on longer in a pool exposed to sunlight and would likely have a faster pH rise and more acid needed as a result.

    Of course, everyone's situation is unique so while most pools operate well at the recommended levels, one can adjust accordingly. Susa, your post above is the first one I see of you mentioning the black algae problem or your changing the CYA level down to 20 ppm. At this time of year, the sunlight is less intense and not all days are sunny so having a lower CYA level can be OK, but during the middle of the summer let us know if you are able to keep a reasonable on-time for the SWG and whether your acid usage changes.
    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"

Posting Permissions

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