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Thread: Ph just keeps falling

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    Ph just keeps falling

    FC 16
    Ph 7.0
    TA 100
    CH 100
    CYA 80

    I started the year with a Ph of 7.2., so I aerated for a week and brought it up to 7.6. I was told then that should watch and make sure the Ph doesn't go any higher as it has a tendency to rise with SWG pools. Well over the last few weeks I've slowly watched the Ph fall, and it's now down to 7.0.

    So first, why does it keep falling? Is this normal? Am I doing something wrong?

    Second how important is it to bring it back up?

    Lastly, if I do need to bring it up, is aerating my only option? I don't really want my TA to get much higher.

    (P.S. I know my FC is a little high, I'm just coming down off a shock and I'm trying to get my generator dialled in again)
    27' AG Round (~17000 Gallons or 64000 L)
    Hayward 1.5 HP Power Flo Matrix Pump (2 speed usually run 6hrs high 18hrs low)
    Hayward CC150CAN XStream Cartridge Filter (150 ft^2 120 GPM)
    Hayward AquaTrol SWG
    Installed April 2012

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    Re: Ph just keeps falling

    I have the same issue, so curious to see what others say. I think mine is caused by needing to do a lot of topping off (evaporation and possibly a leak) with water from my well, which has a pH of 6.9. I've also been adding CYA, which lowers pH. Have you been adding water? To raise pH I've been doing a combo of aerating and borax. Borax will raise TA a little, so maybe not a solution for you.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

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    Mod Squad pooldv's Avatar
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    Re: Ph just keeps falling

    With TA at 100 and an SWG I would expect PH to rise. Does your fill water have low PH? Have you had much evaporation? Or acid rain?

    Aeration or borax are the best ways to raise it. It is important to keep it 7.2 or higher. Having your TA go up is not an issue if it doesn't cause your PH to rise.
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    Re: Ph just keeps falling

    I haven't been filling much this year (only once) and our fill water is supposed to be fairly basic here in Ottawa (>8.5) though I've never tested it myself. It's been a bad year for evaporation, but I keep a solar blanket on so that reduces evaporation some. It's also been rather dry so I doubt it's acid rain.

    Just to confirm the main problem of TA being too high is that it will generally cause the Ph to slowly rise. That said if my Ph is slowly falling right now, then maybe a little more TA might be a good thing?

    Also, I don't really have time to aerate the Ph up again so I guess I'm going to need to use a chemical method of raising. it. What's the advantage of using borax to raise Ph vs soda ash? Does one raise the TA more than the other? I can get the soda ash (pool ph booster from the local hardware store) for 1/3 the amount of the borax so if there isn't a significant advantage to the borax I think I'd prefer to use the soda ash.
    27' AG Round (~17000 Gallons or 64000 L)
    Hayward 1.5 HP Power Flo Matrix Pump (2 speed usually run 6hrs high 18hrs low)
    Hayward CC150CAN XStream Cartridge Filter (150 ft^2 120 GPM)
    Hayward AquaTrol SWG
    Installed April 2012

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    Re: Ph just keeps falling

    Washing soda increases pH and TA more, by a lot. Check out the Effects of adding chemicals section at the bottom of pool math.

    I'd check the pH of that fill water.
    32K gallon Plaster - 1hp Hayward 2 speed Super Pump - Hayward S200 Sand Filter - TF100XL
    Test Kits - Pool Math - Chlorine/CYA/Target/Slam Chart

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    Re: Ph just keeps falling

    Quote Originally Posted by Mr Bruce View Post
    Washing soda increases pH and TA more, by a lot. Check out the Effects of adding chemicals section at the bottom of pool math.

    I'd check the pH of that fill water.
    Oh ya, I've never seen that section before. So soda ash would add more or less twice as much TA as the Borax so I guess that's reason enough to go with the borax. Too bad it's so expensive here in Canada.

    As for the Ph of fill water, I use standard Ottawa tap water. According to the city, they Ph adjust it to between 8.4 and 9.2 so that it's not corrosive to pipes and in turn doesn't leach lead into the water system. I'd be VERY surprised if it's that much lower
    27' AG Round (~17000 Gallons or 64000 L)
    Hayward 1.5 HP Power Flo Matrix Pump (2 speed usually run 6hrs high 18hrs low)
    Hayward CC150CAN XStream Cartridge Filter (150 ft^2 120 GPM)
    Hayward AquaTrol SWG
    Installed April 2012

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    Re: Ph just keeps falling

    Quote Originally Posted by da_guy2 View Post
    Oh ya, I've never seen that section before. So soda ash would add more or less twice as much TA as the Borax so I guess that's reason enough to go with the borax. Too bad it's so expensive here in Canada.

    As for the Ph of fill water, I use standard Ottawa tap water. According to the city, they Ph adjust it to between 8.4 and 9.2 so that it's not corrosive to pipes and in turn doesn't leach lead into the water system. I'd be VERY surprised if it's that much lower
    One thing I've learned here at TFP is to never assume anything (Felix Unger had a great explanation why), check that PH yourself to positively rule out your fill water as a source of your PH falling.

    According to your signature info, you've had this pool for a few seasons now, has the PH always fallen, or is this something new?

    How do you chlorinate the pool, and what do you routinely add to the pool besides chlorine?

    How do you test your water (what test kit do you have)?

    Any recent pool $tore potions?

    Dom
    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!

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    Re: Ph just keeps falling

    Quote Originally Posted by domct203 View Post
    One thing I've learned here at TFP is to never assume anything (Felix Unger had a great explanation why), check that PH yourself to positively rule out your fill water as a source of your PH falling.

    According to your signature info, you've had this pool for a few seasons now, has the PH always fallen, or is this something new?

    How do you chlorinate the pool, and what do you routinely add to the pool besides chlorine?

    How do you test your water (what test kit do you have)?

    Any recent pool $tore potions?

    Dom
    Last year I accidentally raised the TA a bit too high (140). I was told it would likely cause my PH to slowly rise, but it held steady around 7.4 all year. So maybe had my TA been lower to start with it would have fallen last year as well? Not sure. In the past years, I haven't had any problems with Ph.

    This year all I've added to the pool was Salt, CYA, and a few gallons of chlorine to shock.

    As for testing, I test every 1-2 days with strips and 1-2 weeks with a K-2006 test kit. So far the test strip numbers more or less line up with the test kit.
    27' AG Round (~17000 Gallons or 64000 L)
    Hayward 1.5 HP Power Flo Matrix Pump (2 speed usually run 6hrs high 18hrs low)
    Hayward CC150CAN XStream Cartridge Filter (150 ft^2 120 GPM)
    Hayward AquaTrol SWG
    Installed April 2012

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    Mod Squad pooldv's Avatar
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    Re: Ph just keeps falling

    Yes, raise that TA a bit and see what happens.
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    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

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    Re: Ph just keeps falling

    My Father had another idea I thought I'd run by you. Right behind the pool is an oak tree that regularly drops leaves in the pool. It's not like the pool is full of oak leaves but there's always some in there no matter how often I clean them out. Well, it turns out that oak leaves can be somewhat acidic. Could this be the reason the Ph keeps falling?
    27' AG Round (~17000 Gallons or 64000 L)
    Hayward 1.5 HP Power Flo Matrix Pump (2 speed usually run 6hrs high 18hrs low)
    Hayward CC150CAN XStream Cartridge Filter (150 ft^2 120 GPM)
    Hayward AquaTrol SWG
    Installed April 2012

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    Re: Ph just keeps falling

    Quote Originally Posted by da_guy2 View Post
    My Father had another idea I thought I'd run by you. Right behind the pool is an oak tree that regularly drops leaves in the pool. It's not like the pool is full of oak leaves but there's always some in there no matter how often I clean them out. Well, it turns out that oak leaves can be somewhat acidic. Could this be the reason the Ph keeps falling?
    That's a great theory, but I would think you would need an awful lot of leaves steeping for some time to effect 17K gallons.......

    Interesting non the less, you never know ........

    Dom
    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!

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    Re: Ph just keeps falling

    I'd bet that yours if one of the pools that just prefers a higher TA. As others have said, bump it up and see what happens.
    John - 16,000 gallon | in ground | pebble | Triton II sand filter | TF100 | speedstir | Hayward Phoenix 2x

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