Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 13 of 13

Thread: Calcium Hardness

  1. Back To Top    #1

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Calcium Hardness

    I'm new to the forum, but have been lurking all summer and learning a lot. I have a concern I thought I would ask the experts here, before I run myself into trouble. My calcium hardness has been dropping, started out at 250 and dropped to 230. I believe this is likely due to adding water, since my outside bib is pulling water through my water softener. I am using the Taylor K-2006 test kit. Here's my numbers as of today:

    Temp - 80 degrees
    FC - 4.2
    pH - 7.5
    TA - 100
    CH - 240
    CYA - 100+
    Borates - 0
    TDS - 500
    CC - .2

    I'm using PoolPal on my phone as a guide and using the Taylor tables as a cross reference. I've been trying to get my CH back up to 250. I have a 50lb bag of Calcium Chloride flakes 77% minimum according to the package. I added 8 lbs of Calcium Chloride expecting the hardness to move up 20ppm, but it only went up 10ppm (230->240), so I added another 5 5lbs, but the hardness didn't move at all. So, I'm considering adding another 5 lbs, but thought I would check in here first. Is this normal?

    I know my CYA is high, I plan to deal with that post winter. Also, my Chlorinator is set OFF, getting off pucks.
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  2. Back To Top    #2
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    Location
    DFW, TX
    Posts
    23,999

    Re: Calcium Hardness

    The test is +/- 10 ppm, so some variance there. If your CH tends to drift down it is fine to raise it to around 300 ppm in one shot to make it easier. Anywhere from 250 to 350 is good.
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

  3. Back To Top    #3

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Re: Calcium Hardness

    So you're saying just keep adding Calcium Chloride until I hit the numbers I like? Even though the ppm calculations aren't working out? BTW, 300 would be another 26 lbs!
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  4. Back To Top    #4

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,085

    Re: Calcium Hardness

    We suggest you use PoolMath on our site. It's what we know and it seems to on the money.

    Do you have a spigot that bypasses the softener?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  5. Back To Top    #5
    banditig's Avatar
    Join Date
    Sep 2015
    Location
    Ohio
    Posts
    464

    Re: Calcium Hardness

    Since you're not going to use pucks any more, when you need more chlorine you can use calcium hypochlorite to raise CH.
    but of course always test
    15x54 swim & play vinyl metal wall AG
    Hayward S210T sand filter 1.5 HP Pentair Superflo vs
    Rheem raypak 130,000 BTU mv ng
    Jacuzzi 345 whirlpool bath
    TF-100 test kit, HM digital com100 Wanda the Whale

  6. Back To Top    #6

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Re: Calcium Hardness

    Quote Originally Posted by duraleigh View Post
    We suggest you use PoolMath on our site. It's what we know and it seems to on the money.

    Do you have a spigot that bypasses the softener?
    PoolMath gives me the same results, 4.4lbs to raise 10ppm. I've added 13 lbs and only moved 10ppm... weird.

    Yes, I can bypass the softener for the whole house while filling the pool.

    - - - Updated - - -

    Quote Originally Posted by banditig View Post
    Since you're not going to use pucks any more, when you need more chlorine you can use calcium hypochlorite to raise CH.
    but of course always test
    Thanks, been using 6% bleach.
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  7. Back To Top    #7


    TFP Guide

    domct203's Avatar
    Join Date
    Jun 2015
    Location
    CT
    Posts
    3,375

    Re: Calcium Hardness

    Your FC is way too low for your CYA.

    You should do an extended CYA test to determine a better CYA level, then keep your FC greater than 7.5% of your CYA.

    Start at step# 9:
    Pool School - CYA
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

  8. Back To Top    #8

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Re: Calcium Hardness

    Quote Originally Posted by domct203 View Post
    Your FC is way too low for your CYA.

    You should do an extended CYA test to determine a better CYA level, then keep your FC greater than 7.5% of your CYA.

    Start at step# 9:
    Pool School - CYA
    Is there a relationship between CYA levels and Calcium hardness?
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  9. Back To Top    #9


    TFP Guide

    domct203's Avatar
    Join Date
    Jun 2015
    Location
    CT
    Posts
    3,375

    Re: Calcium Hardness

    Quote Originally Posted by desmolift View Post
    Is there a relationship between CYA levels and Calcium hardness?
    Other than both effect your CSI, no.
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

  10. Back To Top    #10

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Re: Calcium Hardness

    Ok... Got the CH to 260, added another 6 lbs of Calcium Chloride. So in all it took me 19lbs to move from 230 -> 260. I guess if the test variation is +/-10ppm then on the high side I would have been trying to move 40ppm which would have taken 18lbs. So on a stretch, I guess its within the margin of error.
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  11. Back To Top    #11


    TFP Guide

    domct203's Avatar
    Join Date
    Jun 2015
    Location
    CT
    Posts
    3,375

    Re: Calcium Hardness

    Quote Originally Posted by desmolift View Post
    Ok... Got the CH to 260, added another 6 lbs of Calcium Chloride. So in all it took me 19lbs to move from 230 -> 260. I guess if the test variation is +/-10ppm then on the high side I would have been trying to move 40ppm which would have taken 18lbs. So on a stretch, I guess its within the margin of error.
    More importantly, where is your FC?
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

  12. Back To Top    #12

    Join Date
    Aug 2016
    Location
    CT
    Posts
    7

    Re: Calcium Hardness

    Quote Originally Posted by domct203 View Post
    More importantly, where is your FC?
    Near 8.5 today. Measured CYA is coming in at 170, not sure how accurate this is given the 50/50 split of tap water. Recommendation for this is FC -> 13-20. Running with FC at 3-5, I'm getting algae growth on the walls after about 4 days, brush and vacuum. I'm increasing FC and watching for results, taking careful steps, while keeping the pool balanced.
    20'x40' in-ground, gunite, 36,000 gal, Sta-Rite System 3 S8M150 filter, Sta-Rite Max-E Glas II pump, Sta-Rite Max-E Therm Heater, Chlorinator

  13. Back To Top    #13


    TFP Guide

    domct203's Avatar
    Join Date
    Jun 2015
    Location
    CT
    Posts
    3,375

    Re: Calcium Hardness

    If your CYA is 170ppm, your minimum FC is 13 (7.5%), target FC is 22ppm (13%), shock level is a whopping FC 68ppm.

    If you have visible algae you need to lower that CYA more so you don't have to "break the bank" to pay for the chlorine needed to eliminate it. You will need to exchange most of the water in your pool. If you drain then refill half the volume of the water, the CYA will drop by 50%, getting you to around 90ppm (85 rounded up). Another 50% exchange will get you to 40-50ppm, which now only requires a shock FC of 16-20ppm.

    Be careful with large drains (>40%), While it hasn't been too wet this season, a high water table can and will pop your pool shell out of the ground.
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

Posting Permissions

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