Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: New Pool with Very High CYA

  1. Back To Top    #1

    New Pool with Very High CYA

    I just moved into a house with a 17,500 gal IG plaster pool. First time pool owner. It's in good condition, and I'm getting closer on the water chemistry. For the first two weeks I was targeting (and getting) 4-5 FC. But I just tested CYA with the TFP test kit (and took water to the local pool store to double check my test), and CYA is between 120 and 150. The BBB FC/CYA chart only goes to CYA of 100, with a target FC of 12. Chem Geek's post goes to CYA of 120, with a target FC of 13.6. I'm having moderate problems with Mustard Algae; meaning I'm scrubbing and brushing just about every time I'm in the pool, obviously because FC has been too low. And Chem Geek's chart targets 17+ FC to combat algae at high CYA.

    Here's the question - it doesn't seem particularly safe/comfortable to swim in water with FC of 17+. Any opinions on keeping FC that high permanently? Bottom line is that it seems I'll need to drain and refill to fix the CYA problem.

  2. Back To Top    #2

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,406

    Re: New Pool with Very High CYA

    Here's the question - it doesn't seem particularly safe/comfortable to swim in water with FC of 17+. Any opinions on keeping FC that high permanently? Bottom line is that it seems I'll need to drain and refill to fix the CYA problem.
    The only permanent solution is a partial drain/refill as you suspect. Go ahead and bite the bullet unless your swim season is about to close......if so, the CYA may dilute a lot over the winter.

    It is perfectly safe to swim in it because the high CYA makes the effective chlorine much lower than the 17ppm that may be there. Nevertheless, running high CYA and subsequent high chlorine makes the pool very difficult to manage. Your beswt bet is to get your CYA down around 50.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    21,774

    Re: New Pool with Very High CYA

    With CYA that high, your best bet is to drain as much water as you can and refilling. The final number needs to be in the neighborhood of 2/3rds reduction. Be particularly aware of your water table, you don't want your pool poping out of the ground. You can do the drain/refill in increments but remember that you'll have to drain a total of more that 2/3rds of the total gallons to get a 2/3rd reduction in CYA doing it that way.

    Dave and I were typing at the same time.
    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

  4. Back To Top    #4

    Re: New Pool with Very High CYA

    Thanks for the feedback - as I suspected.

  5. Back To Top    #5

    Re: New Pool with Very High CYA

    Just a quick "learn from my mistake" update: I did drain the pool to rid myself of the CYA. Took the time to acid wash, fix light, hit stains, etc. Started the refill of the 17K gals 2pm on Saturday. By Sunday morning we were within 8 inches. I turned the flow down and we went to church, visited a friend, went to lunch and back by 2pm.

    The pool was 2/3 empty!

    Here's the lesson: when you drain a pool using the backwash setting, don't forget to reset the pump to "filter", or your timer will kick on like usual and drain your hard work away!

  6. Back To Top    #6

    Re: New Pool with Very High CYA

    Quote Originally Posted by strongcedar
    Just a quick "learn from my mistake" update: I did drain the pool to rid myself of the CYA. Took the time to acid wash, fix light, hit stains, etc. Started the refill of the 17K gals 2pm on Saturday. By Sunday morning we were within 8 inches. I turned the flow down and we went to church, visited a friend, went to lunch and back by 2pm.

    The pool was 2/3 empty!

    Here's the lesson: when you drain a pool using the backwash setting, don't forget to reset the pump to "filter", or your timer will kick on like usual and drain your hard work away!
    Homer says it best: (that really sucks though )
    Attached Images Attached Images
    Jacuzzi 12x24 Oval AG 48" about 7500G
    Jacuzzi Maxiplus 190 sand
    Sta-rite/aquatools 2 speed 1HP (JWP series)
    Intex 8110 SWG

Posting Permissions

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