Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 15 of 15

Thread: What can drive alkalinity up?

  1. Back To Top    #1
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    What can drive alkalinity up?

    At the begining of the season my TA was 90 and now it's 110.
    The only reagents that may have contributed to the rise that I can think of are :
    1. I used a combination of 97% boric acid and 3% borax to get 50 ppm borates. I don't recall if I measured TA after the addition.
    2. I sometimes use left-over CalHypo instead of bleach to adjust FC.
    Other numbers:

    CYA : 33
    FC : 2 - 3
    CC: < 0.5
    CH: 250
    pH : 7.3 - 7.4
    Temp 82 - 87
    Salt 3600 ppm
    borates 50 ppm
    and lots and lots of crystal clear "sweet" water.
    Can someone tell me if this rise in TA is common and what's the reason for it.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  2. Back To Top    #2
    spishex's Avatar
    Join Date
    Oct 2008
    Location
    Hillsborough, NC
    Posts
    1,375

    Re: What can drive alkalinity up?

    Do you know the TA of your fill water?

  3. Back To Top    #3

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

    Re: What can drive alkalinity up?

    My TA slowly rises over time due to the fill water having 80 ppm. With evaporation and refill, anything in the fill water gets added to what is in the pool.
    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
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    Re: What can drive alkalinity up?

    My fill water has a TA of 50.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  5. Back To Top    #5
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    Location
    SW Indiana
    Posts
    9,089

    Re: What can drive alkalinity up?

    A TA reading isn't going to be consistent unless both readings are taken at the same pH. A slight pH rise will also cause a TA rise.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  6. Back To Top    #6

    Join Date
    Jan 2009
    Location
    Cupertino, CA
    Posts
    1,966

    Re: What can drive alkalinity up?

    Listen to chem geek.
    Quote Originally Posted by chem geek
    With evaporation and refill, anything in the fill water gets added to what is in the pool.
    So, if your fill water's TA is not zero, then any time you add water you are increasing your TA.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  7. Back To Top    #7
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    Re: What can drive alkalinity up?

    Quote Originally Posted by PaulR
    Listen to chem geek.
    Quote Originally Posted by chem geek
    With evaporation and refill, anything in the fill water gets added to what is in the pool.
    So, if your fill water's TA is not zero, then any time you add water you are increasing your TA.
    --paulr
    My dilution with rain water was a lot more significant than the recent 1 - 2 inches refill with fill water due to evaporation, so it doesn't seem likely that my 22% increase in TA is the result of adding 1-2 inches of water with TA 50.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  8. Back To Top    #8

    Join Date
    Jan 2009
    Location
    Cupertino, CA
    Posts
    1,966

    Re: What can drive alkalinity up?

    You're right, that doesn't make sense. I tested rain water once and TA was too low to measure.

    I have sometimes wondered if leaves falling in the pool can contribute to TA. But that's just idle speculation.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  9. Back To Top    #9

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

    Re: What can drive alkalinity up?

    The TA test measures any ionic compounds that can accept a hydrogen ion down to a pH of 4.5. Normally, this is mostly bicarbonate plus some cyanurate (from CYA) and a small amount of borate (if used). I suppose there might be some organic weak acids that also contribute but I doubt there is enough to register on the test. There is also some effect from the starting pH (i.e. hydroxyl ions), but in the normal pool pH range this effect is fairly small (moving from 7.2 to 8.0 using a pure base at a TA near 100 ppm would increase the TA around 10 ppm).
    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"

  10. Back To Top    #10
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    Re: What can drive alkalinity up?

    chem geek: Did you notice a TA increase after you added 50 ppm borates?
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  11. Back To Top    #11

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

    Re: What can drive alkalinity up?

    Only barely -- hard to distinguish given test error. 50 ppm Borates at a pH near 7.5 would only increase TA by about 5 ppm (at a pH of 8.0 it would raise the TA by about 15 ppm so it's a little more noticeable at higher pH targets).
    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"

  12. Back To Top    #12
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    Re: What can drive alkalinity up?

    Retested my TA and it's 110. I know I tested more than once upon openening this season and it was 90. Based on what was written so far I don't think we have a plausible explanation why the TA has gone up. I'll recheck CH and see if it has changed too. I wonder how common is this up moving level of TA.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  13. Back To Top    #13

    Re: What can drive alkalinity up?

    Do you have natural rocks or stone or natural tiles that touch your water?
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

  14. Back To Top    #14
    Water_man's Avatar
    Join Date
    Jun 2008
    Location
    Brookline, MA
    Posts
    390

    Re: What can drive alkalinity up?

    Quote Originally Posted by anonapersona
    Do you have natural rocks or stone or natural tiles that touch your water?
    No.
    This is my ticket for Heaven (when all's working..) :
    22k Gal gunite IGP, 38 SF Anthony DE filter, 1 HP Hayward Super Pump
    380k BTU Raypak Natural Gas Heater (Model RP405A) and solar cover
    8 gal Liquidator w/ 12% bleach, Dolphin Diagnostic Advantage robotic cleaner. 3800 ppm salt, 50 ppm borates.

  15. Back To Top    #15

    Join Date
    Jan 2009
    Location
    Cupertino, CA
    Posts
    1,966

    Re: What can drive alkalinity up?

    Quote Originally Posted by Water_man
    Retested my TA and it's 110. I know I tested more than once upon openening this season and it was 90.
    Ya know... I think this is fussing too much. The sensitivity of the test is +/- 1 drop or +/- 10ppm, so going from 90 to 110 is at the outside edge of the actual uncertainty. Sorry I didn't look closely enough at the actual numbers the first time around.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

Posting Permissions

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