Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 7 of 7

Thread: Do I care that my CH is high? What problems will it cause?

  1. Back To Top    #1

    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    282

    Do I care that my CH is high? What problems will it cause?

    Quick background:

    Salt water pool, gunnite finish. I had a major calicum scaling problem when the pool was opened this spring (2nd year of use). I did two no-drain acid washes which pretty much took care of the problems. I've been testing my water and I know I have a couple problems that I'm dealing with and one problem (calcium hardness) that I'm not dealing with (don't want to replace 15,000 gallons of water).

    My question is, what are my problems/risks/issues with keeping the calcium hardness higher than normal until evaporation/spashing causes enough water loss and replacement to bring things back to normal?

    My latest pool store test results are below, but I'm a little suspect of some of the numbers (I got a higher CYA number (and so did they) a couple weeks ago before I added more CYA!) (Original CYA number was 55, but after adding 10 lbs of CYA it's down to 45!?!?!?) Doesn't make sense. Also the CH number was around 640 two weeks ago and now it's 375. Doesn't make sense!

    Anyhow, here are todays numbers from the pool store (I tested too, but forgot my numbers at home

    FC 1.0
    CC 1.0
    pH 7.4
    T/A 145 (it was about 185, but I've been bringing it down)
    CH 375 (two weeks ago it was 640)
    CYA 40 (two weeks ago it was 55. I've since added 10 lbs CYA)
    Total Disolved Solids 4500

    The remedy for the high total hardness (CH) was to add 3 quarts of Scale Inhibitor accounding to the print out from the pool store.

    Two questions:

    1) Should I bother with the Scale Inhibitor or is that snake oil?
    2) Can I just wait out the high hardess levels without doing major damage to people/equipment/pool?

    Actually, a third question: Should I be concernend about my high total disolved solids number? I don't recall people testing for that or talking about it.

    Thanks!!
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    Location
    SW Indiana
    Posts
    9,089

    Re: Do I care that my CH is high? What problems will it cau

    Calcium doesn't leave the pool when water evaporates. I'd be very suspicious of your readings. Since you've already had scaling, you need to be careful to avoid it again. What is the CH of your tap water?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Do I care that my CH is high? What problems will it cau

    If your CH level is 375, then you are just fine as far as calcium goes. If CH and TA and PH are all high then you can get calcium scaling. Your CH and TA levels are both just slightly high (now that you brought them down) and PH is just slightly low, so that should be fine. Scale inhibitor would help if CH was higher.

    I hope your CC level isn't actually 1. Perhaps you meant TC? If CC is actually 1 you need to shock the pool.

    Just ignore TDS. TDS is a total, which is unimportant. What matters is what the individual levels are.

    It is clear that your pool store testing is not reliable. You would have a much simpler time if you had your own top quality test kit.
    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

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

    Re: Do I care that my CH is high? What problems will it cau

    1. The scale inhibitor is most likely a sequetrant and it can help a little in certain circumstances.
    If your CH is really 375 it's pretty manageable without any scale inhibitor.
    Keep your pH on the low end and get your TA down to about 70 and you should be fine

    2. You can wait it out unless your fill water is also hard, in which case it's going to constantly get worse. Keep in mind that CH doesn't evaporate so you can't count on that as helping. Splashout and backwashing is about all you have going for you.

    3. About 3500 ppm or so of that TDS number is your salt so I wouldn't worry about it.
    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

    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    282

    Re: Do I care that my CH is high? What problems will it cau

    Quote Originally Posted by JohnT
    What is the CH of your tap water?
    Don't know the answer to that one. We're on well water in Northern VA/Blue Ridge Mts. if that helps. Another data point is that last year was the first year of use of the pool and it was filled via tanker trucks. I found some test results that I posted last August and my CH was 250.

    Since then, I've only added maybe a foot or two of water (not sure how many gallons that is, but it has to be a pretty small percentage of the total amount)
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  6. Back To Top    #6

    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    282

    Re: Do I care that my CH is high? What problems will it cau

    Quote Originally Posted by JasonLion
    I hope your CC level isn't actually 1. Perhaps you meant TC? If CC is actually 1 you need to shock the pool.

    It is clear that your pool store testing is not reliable. You would have a much simpler time if you had your own top quality test kit.
    Yep! Sorry about that typo. My TC is 1.

    I do own the TF100 kit and will be rechecking my results tomorrow. I just added some CYA last weekend (after testing) and my results were 55. I pulled a sample last night and was hoping to see it climb a little after 5 days in the water, but you're right, the pool store is not reliable.
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  7. Back To Top    #7

    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    282

    Re: Do I care that my CH is high? What problems will it cau

    Quote Originally Posted by Bama Rambler
    2. You can wait it out unless your fill water is also hard, in which case it's going to constantly get worse. Keep in mind that CH doesn't evaporate so you can't count on that as helping. Splashout and backwashing is about all you have going for you.

    .
    Thanks Bama.

    That's what I meant to imply.....it would come down as I added more water, not as the current water evaporated.

    Need to be more clear!!
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

Posting Permissions

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