Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 10 of 10

Thread: Reverse Osmosis to remove CYA?

  1. Back To Top    #1

    In the Industry


    Join Date
    Jul 2012
    Location
    Saugerties, NY
    Posts
    447

    Reverse Osmosis to remove CYA?

    I was browsing around on the internet, and I came across a thread where someone recommended using reverse osmosis to filter out calcium from pool water, and they warned that it would also remove CYA in the process. My knowledge on reverse osmosis is somewhat limited, so I'm hoping someone here might be able to confirm this.

    I'm thinking that if this could work, it might be an option for treating some of the pools I run into that have accumulated CYA and still rely on tablets for chlorination.

    Most of the RO systems I've seen are 5 stages. Do each of these stages remove different types of impurities? Would I be able to take one or two stages to remove Calcium and CYA?
    TreeFiter

    Pool Technician
    Saugerties, NY

  2. Back To Top    #2

    In the Industry

    Donldson's Avatar
    Join Date
    Jun 2009
    Location
    NW Ohio
    Posts
    2,637

    Re: Reverse Osmosis to remove CYA?

    It removes pretty much everything from the water. I don't know too much about the process specifics, but I do know it is not a selective thing. There is no "CYA removal stage". It runs around $500 to treat a single pool, which is why it is only available in the Southwest where water is at a premium. I doubt it would be a financially viable option in the Northeast.
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

  3. Back To Top    #3
    Mod Squad woodyp's Avatar
    Join Date
    Apr 2010
    Location
    East Texas
    Posts
    8,999

    Re: Reverse Osmosis to remove CYA?

    I'm wondering if those 5 stages you are referring to are 5 different membranes-----each progressively filtering out to a smaller micron level?
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

  4. Back To Top    #4
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
    Posts
    22,347

    Re: Reverse Osmosis to remove CYA?

    If you're thinking about household units, those R/O units have a prohibitively high rejection rate, so they're not suitable for treating large amounts of water.
    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

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Reverse Osmosis to remove CYA?

    Pool RO systems are fairly complex. They require pre-treatment stages to remove things which can damage the membrane, and they use extremely high pressure pumps. There are several groups nationwide who have figured it out, but they don't document exactly what they have done. As a result, setting up your own system is still quite complex.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. Back To Top    #6

    In the Industry


    Join Date
    Jul 2012
    Location
    Saugerties, NY
    Posts
    447

    Re: Reverse Osmosis to remove CYA?

    Thank you all for your replies. I was thinking it might not be a bad idea if I could use a system similar to what they install in a house. You can pick up a low end system for about $150. I was hoping to be able to set it up on an auxiliary system and leave it for a week or so, but it sounds like it wouldn't be that easy.
    TreeFiter

    Pool Technician
    Saugerties, NY

  7. Back To Top    #7
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Reverse Osmosis to remove CYA?

    Home RO systems send more water to the drain then they process. For pool use that means they aren't much better than draining and refilling.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  8. Back To Top    #8
    Isaac-1's Avatar
    Join Date
    May 2010
    Location
    SW Louisiana
    Posts
    6,711

    Re: Reverse Osmosis to remove CYA?

    The other problem is Home RO systems can't handle the higher osmotic pressures usually needed for this kind of operation.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from http://tftestkits.net
    ~Remember TFP counts on your donations to keep this site ad free~

  9. Back To Top    #9

    Join Date
    Jun 2014
    Location
    Houston, TX
    Posts
    3

    Re: Reverse Osmosis to remove CYA?

    I have seen waste numbers on RO as high as 5 to 1. Three, four, and five stage units all contain just one membrane. Additional stages just increase time between servicing. If my memory serves me correctly a three stage is particulate, carbon, membrane. Four stage is large micron particulate, small micron particulate, carbon, membrane. I think the five stage adds another absorption filter of some type. RO membranes can not handle chlorine so breakthrough of the aborbtion portion of the unit is also the end of membrane life.
    7600g round 18ft installed spring 2012
    AG buried 30" IG w/Hayward sand model 210T with Hayward single speed 1.5HP ~3000gph
    AquaTrol SWG
    "Wedding Cake" steps in pool (pain in my neck)

  10. Back To Top    #10

    Re: Reverse Osmosis to remove CYA?

    An ro would remove CYA and if you went with CA membranes (cellulose acetate), they can handle the chlorine. The unit would be very cost prohibitive though. A small 50 GPM system (3 membrane first stage, 2 second, one third) would run in the $100-$150k range. The household units that are much cheaper only recover about 30% of the water you put in.

    Also, a CA system will only return 50-60% of the water removed back into the pool (the rest would have to go to waste) and that is for a 3 stage system making a simple drain and refill MUCH more cost effective anyway. Even a PA membrane 3 stage system rejects about 25% and it will quickly be destroyed by chlorine.

    Usually the more stages to a system, the better your recovery is. In a 3 stage system, the reject from the first stage of membranes passes into the next stage and you recover more clean water then the reject from that stage passes through the third stage.

    That's also not taking into account the cost of the pre-filters needed ahead of the RO. RO membranes are designed to remove salt not debris. Any debris in the water (even down to dissolved flocculant or tannins) will destroy the membranes in a VERY short time.
    Using Tapatalk

Posting Permissions

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