Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 17 of 17

Thread: Target numbers to reduce rising pH?

  1. Back To Top    #1

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148

    Target numbers to reduce rising pH?

    I was hoping someone could recommend some target numbers for TA (or anything else) that could reduce my pH rise. I use only sodium hypochlorite (10%) for chlorination. I have been intending to go with borates for quite some time now (and still may) but I just haven't done it. Besides, I have a really good aerator that I built myself which connects to the return, and I'm looking for an excuse to finally use it .

    My readings as of last night (all obtained with Taylor tests):
    FC 3.0 (fas-dpd)
    CC 0 (fas-dpd)
    pH 7.5
    TA 130
    CH 130 (residual from my pre-BBB days. coming down gradually)
    CYA <30 (I'm calling it 20 for now. added some cya a few days ago. will restest this weekend)

    Many thanks ...
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  2. Back To Top    #2
    a TA of 90-120 is usually recommended...

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

  3. Back To Top    #3

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Quote Originally Posted by The Mermaid Queen
    a TA of 90-120 is usually recommended...
    Thanks MQ. The 90-120 is the "standard" range, or so I thought. I believe even lower ranges can be utilized to offset rising pH, but I don't know what that would be.
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  4. Back To Top    #4

    Re: Target numbers to reduce rising pH?

    Chem geek has a chart that shows the outgassing ranges at various PH/Alk levels. Not sure where it is though.

    Quote Originally Posted by Poseidon
    I have a really good aerator that I built myself which connects to the return, and I'm looking for an excuse to finally use it .
    How about a little more about this?


  5. Back To Top    #5

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148

    Re: Target numbers to reduce rising pH?

    Quote Originally Posted by Rangeball
    Chem geek has a chart that shows the outgassing ranges at various PH/Alk levels. Not sure where it is though.

    Quote Originally Posted by Poseidon
    I have a really good aerator that I built myself which connects to the return, and I'm looking for an excuse to finally use it .
    How about a little more about this?

    I built it out of 1 1/2" PVC. I unscrew the eyeball return, and replace it with the aerator. I had to have the threads cut, but other than that, it was all home-made. Working in a manufacturing facility has it's benefits . I'll try to post some pics tomorrow.
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  6. Back To Top    #6
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887
    I generally recommend a TA of 80 to 90 when you are not using trichlor/dichlor. I know that several people have gone lower with some success. You can take it quite a bit lower, perhaps 50, if you add borates to 50 ppm. Also, people with plaster pools need to keep their saturation index in mind, perhaps raising calcium to compensate for the lower alkalinity.

    It also helps to allow your PH to go up a bit, perhaps to 7.6 or 7.7. Of couse raising PH isn't such a great idea if you have issues with metals in the water.
    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

  7. Back To Top    #7

    Join Date
    Apr 2007
    Location
    Ohio
    Posts
    217
    Hi Poseidon
    I cant tell you what to do but i will share my numbers to start i live in north Ohio it has ben dry this year and hot for Ohio 90 deg. now. pool is also at 88 deg. open to low numbers on everything so i had to work my way up. I opened on april 20. These are my numbers i just took them so i could pass them on to you.
    FC 3.0
    CC 0
    PH 7.5 (This has bin rock solid and i have added no acid all year)
    TA 90
    CH 100
    CYA 30
    Borates 30( was going to go higher but this is working out well)
    Hope this is some help to you
    Ric W
    My Pool
    8605 gal fiberglass, 3/4 hp pump, sand filter, aquabot cleaner, heat siphon heat pump, tiger river(sumatran) spa

  8. Back To Top    #8
    Guest
    uncorrected TA between 70-90, pH 7.6 and lower it back down when it hits 7.8, CH around 250-300. This seems to work well for reducing acid consumption with unstabilized chlorine.

  9. Back To Top    #9

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    This chart shows the relative rate of carbon dioxide outgassing which will be proportional to the amount of acid you have to add over time (but not the pH rise or frequency of addition). As you can see, lowering the TA and raising the pH both have significant effects at reducing the rate of outgassing. The actual rate of outgassing will also be a function of aeration.

    This chart shows the relative rate of pH rise. This takes into account the pH buffering effect from higher TA. So you can see that the effect of lowering TA on the rate of pH rise is small, but measurable while maintaining a higher pH has a more significant effect.

    If you are using a hypochlorite source of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite) then you can have a rather low TA, but probably not lower than 50 ppm to play it safe (if you have Borates, as mentioned by previous posts, then that's better though Borates have more buffer capacity for a rise in pH and less for a large drop). Certainly if you ever use an acidic source such as Trichlor you have to be careful or increase your TA (to 100-120 or more if you will use Trichlor regularly).

    Richard
    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

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Thanks to all for the input. And thanks chem geek for those charts.
    As promised, here's some pics of my home-made aerator.
    Aerator
    Aerator in action
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  11. Back To Top    #11
    WOW! That's a lot of air! Should get your TA down, and right quick!

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

  12. Back To Top    #12
    Thanks for the pics Awesome aeration action Curious, does your pump filter go up when you screw the aerator in?

    My IG pool only has one return, so I've been apprehensive about building something that would limit circulation. I had been considering trying a venturi principle approach. Basicall, a 1.5" section of pvc with a T in the middle, which is screwed into my return (I have 1.5" pipe on all my runs), so the return flow is still fully flowing straight out for circulation. I would then reduce the T to maybe 1/2" or something and screw in a piece of PVC that would stick up above the pool surface. I'm wondering if this would allow the water rushing through the bigger pipe below to draw air via venturi suction, introducing it into the water as small little bubbles but not reducing the overall flow by any appreciable amount.

    It's another thing on my "try this someday" list. Fortunately, rapid PH increase hasn't been a problem this season.

  13. Back To Top    #13

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Quote Originally Posted by Rangeball
    Thanks for the pics Awesome aeration action Curious, does your pump filter go up when you screw the aerator in?

    My IG pool only has one return, so I've been apprehensive about building something that would limit circulation. I had been considering trying a venturi principle approach. Basicall, a 1.5" section of pvc with a T in the middle, which is screwed into my return (I have 1.5" pipe on all my runs), so the return flow is still fully flowing straight out for circulation. I would then reduce the T to maybe 1/2" or something and screw in a piece of PVC that would stick up above the pool surface. I'm wondering if this would allow the water rushing through the bigger pipe below to draw air via venturi suction, introducing it into the water as small little bubbles but not reducing the overall flow by any appreciable amount.

    It's another thing on my "try this someday" list. Fortunately, rapid PH increase hasn't been a problem this season.
    No, my filter pressure does not change. My eyeball return has slots in it. I measured them and calculated the surface area. The holes in the aerator match the surface area of the eyeball slots. However scientific this may or may not be, the pressure is the same. Theoritically I should be pushing the same amount of water through.

    I'm not sure I follow your idea, but it sounds interesting.
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  14. Back To Top    #14
    Quote Originally Posted by Poseidon
    No, my filter pressure does not change. My eyeball return has slots in it. I measured them and calculated the surface area. The holes in the aerator match the surface area of the eyeball slots. However scientific this may or may not be, the pressure is the same. Theoritically I should be pushing the same amount of water through.
    Ahhh... Smart One of my ideas was to plumb something that would screw into my return, use a shallow elbow to get the end of the pipe above the water surface, and have a cap on it with several small holes drilled, enough to match the area of the return hole. I was thinking this would provide the same water volume and hopefully not impede circulation, but the smaller streams would create more and smaller bubbles

    I'm not sure I follow your idea, but it sounds interesting.
    Imagine a piece of pipe that basically extends the return out into the pool a foot or so. Sticking straight up from it is a smaller piece of pipe that has the upper end above the surface of the water. Water flows through the larger pipe in the pool, and the flow creates suction in the smaller pipe, drawing air into the current.

    .............Air
    ............. l
    ............. V

    ............. ||
    ..^^^^^||^^^^^^^^
    _______||_______
    -------->------>----->----->

    Arrow is water flow. Air is sucked downward into water flow through vertical pipe. ^^^^^ is water surface. Ignore the "...", their to make the spacing work

  15. Back To Top    #15

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Rangeball,
    Ahh, I get it now. I'm no expert on this, but wouldn't the water, under pressure as it is, force it's way up and out the vertical piece?
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  16. Back To Top    #16
    I'm thinking it wouldn't. It should take the path of least resistance, and flow straight out.

    It's based on the venturi principle, like a lot of suction intake devices are (chemical hose for running detergent through a power washer, for instance). In theory anyway.

    Problem is I've has so few PH issues this year, I don't have a reason to try it

  17. Back To Top    #17

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    Update. I lowered the TA to 80, and the pH has held steady for a week now. Previously the pH would rise from 7.4 to 7.7 in about 8 days.

    Many thanks.
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

Posting Permissions

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