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Thread: pH dropping but TA isn't??!

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    Tiptoeadventures's Avatar
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    Question pH dropping but TA isn't??!

    We've had it up and running for over a month now and haven't been able to get all the levels right yet or swim. I'm complety new to this and am still learning and reading A LOT on here but some custom advice would save a lot of searching time and my anxiety :/

    I finally got chlorine readings after having absolute none during the first 2 weeks of my SW pool setup but Then we had such high TA and pH levels that the basic test colors are off the chart. I've been running full tests once week for the past 2 weeks and the pH is now normal but the TA hasn't moved. I'm adding about a 1/4 gallon MA but am wondering how long you would guess I'll need to add these amounts and if I should be doing it everyday?

    I also thought that the acid would drop my TA and in turn then drop the pH but I'm seeking the other way around. For the past 3 days the pH level is returning to normal but the yellow side is till out of testing zone?

    The guys who setup my pool scheduled the SWG and pump and I'm not really sure how to mess with that or if I should be scheduling it to run longer than normal until my pool is balanced?

    My my full test results today were:
    62-CYA
    6=TA (6ppm= FC,0=CC )
    110=TA
    pH-7.5-7.8

    I do understand that with Southern California water/sun and a plaster pool that we will need to add MA a lot to keep the levels down, so I'll take 3 gallons of the empty chlorine we needed to get those levels to register in and replace them with MA. Just wondering how many I should have on stock, if it's harmful to be adding so much each day, and if you believe it will level out eventually with continued daily adding, also if I should mess with the scheduled run time to force it to filter/run longer than the normal schedule in order for the chemicals to balance at a faster rate? I'd love to swim in the new pool before summers end
    Last edited by Tiptoeadventures; 08-08-2015 at 09:06 PM. Reason: Wrong terms entered
    17.5k gallon IG plaster ~ 1st time pool owner ~ Resurface & Fill Completed 06/2015
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    Richard320's Avatar
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    Re: pH dropping but TA isn't??!

    If the water is clear and warm enough to suit you, why can't you go swimming? The FC/CYA ratio is good and the pH is in range.

    You had it replastered, correct? Expect to use a bunch of acid for a few months. Too soon to panic.

    The pH rising is the plaster curing and the outgassing from the high TA. The Chlorine climbing might just be that the CYA has peaked and now the SWG has no problem keeping up with the solar load. Turn the SWG down a few percentage points. Less SWG will also slow the pH rise.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    aussieta's Avatar
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    Re: pH dropping but TA isn't??!

    as Richard says your numbers look fine for swimming as long as the water is nice and clear
    lowering ta can be a long term project you dont need to worry too much
    if you lower your ph to 7.2 with muriatic acid that will also slightly lower your ta
    and then aerate the water the ph will go back up
    at ph 7.6 reduce to ph 7.2 again
    easiest way to aerate the water is throw some children in there and let them splash around
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    Tiptoeadventures's Avatar
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    Re: pH dropping but TA isn't??!

    Whew...thank you! Good to know- I've been the debbie downer that tells everyone they can't swim yet until its balanced. Glad to know I can have some fun! Yes, it was a replaster job after it sat emptied for almost 2 years before we acquired the property. It's going to be a vacation rental so getting the chemicals in balance has been a top priority for me since I figure that will be harder to do once there is activity from a lot of people?

    I will keep adding acid daily as I have been doing then Do I need to have concern that it may drop the pH too much while trying to get the TA down? How long would you say after adding my daily dose of MA should I wait to get in the pool? (I'm guessing about 30 minutes if it's running..just enough time to let the acid filter through so I don't come in direct contact with a cloud of it?)
    17.5k gallon IG plaster ~ 1st time pool owner ~ Resurface & Fill Completed 06/2015
    Pentair SWG 3200 ~ FNSplus Vertical Grid D.E Filter ~ Pentair Intelliflo variable speed ~ Purex Triton Minimax Plus 400 Heater (Propane)
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    Mod Squad pooldv's Avatar
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    Re: pH dropping but TA isn't??!

    Yes, 30 minutes after adding acid it is fine to swim. Keep your PH between 7.2 and 7.8 and don't worry about your TA number. They will find equilibrium over time, months, and you won't need to add as much acid. No need to worry about TA level until it is below 60.

    It is important to keep chlorine at target level for your CYA level and never to let it drop below minimum or the pool will not be properly sanitized and algae will grow. It is safe to swim when FC is between minimum and shock level, Chlorine CYA Chart
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    Re: pH dropping but TA isn't??!

    With new plaster, as has been said, your pH will naturally rise until it has fully cured. I wouldn't bother with any special aeration to get the pH up after adding the acid...it'll go up regardless.

    The only thing to keep half an eye on is that adding all that acid WILL knock your TA down...eventually.

    I have new Pebble Sheen on my pool (day 25 since initial fill-up) and my pH is constantly on the rise...stock up on acid.

    My TA finally reached 70 today and I decided to add about 3 quarts of baking soda to bump it back to 90.

    It took all of those 25 days to go from 120 (tap/city water) to 70. I've probably added about 8-10 gallons of MA since initial fill-up. I'm trying to keep the pH in the 7.2 - 7.5 range.

    My chlorine is nice and stable with The Liquidator and my CYA is 40ish. Pool looks fantastic...and it has been used daily since like day 3 or 4 of fill-up.

    You don't list your CH...calcium hardness. You'll want that at around 200 as it should naturally rise over time, too.
    ----Chris----
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    Re: pH dropping but TA isn't??!

    Quote Originally Posted by Agent99 View Post
    It took all of those 25 days to go from 120 (tap/city water) to 70. I've probably added about 8-10 gallons of MA since initial fill-up. I'm trying to keep the pH in the 7.2 - 7.5 range.
    Normally adding 8 gallons of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 25,000 gallons would lower the TA by 155 ppm so your 50 ppm drop implies a TA increase of around 110 ppm. Did your CH increase by roughly 100 ppm? If so, then you may have had either calcium carbonate dissolving into your pool water or calcium hydroxide (or some combination of the two). It would be better to saturate your water with calcium carbonate (even over-saturate it somewhat) to prevent any of this dissolving of calcium carbonate or calcium hydroxide into the pool water. Did you have an acid or traditional start-up instead of a bicarbonate start-up? The calcium carbonate could then be "plaster dust".

    In other words, it is better to NOT have the CH rise over time except from evaporation and refill with water that has CH. You generally do not want calcium coming out of your pool plaster though that does happen during an acid and traditional start-up.
    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
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    Re: pH dropping but TA isn't??!

    chem geek,

    I increased my CH from a very low reading (maybe 40 ish? out of the tap...surprisingly soft) to about 230 using calcium chloride around day 3. I haven't measured it in a week or two but it was at 230 last reading. I'll measure it tonight and see where it is at.

    I think I did a 'traditional' start-up with my Pebble Sheen; I don't know what a bicarbonate or acid start-up is. My Pebble Sheen was acid washed prior to fill-up if that means anything (supposedly that gets rid of a fair amount of dust?). I followed the NPC's guide for a start-up as that is what Pebble Tec had on their web site.

    I also added a 1/2 gal of MA yesterday morning to knock the pH back down and then 3 quarts of baking soda in the afternoon to get my TA to 90 from 70 although I haven't yet verified my new TA with a reading...I'll do that tonight as well.
    ----Chris----
    25k IG/Spa Figure 8, 18x36, Pebble Sheen Blue Granite, Sta-Rite S8M150 Cartridge Filter, Pentair 460805 400k BTU Heater & 011018 IntelliFlo VarSpd
    Liquidator, Fafco Solar Heat, Polaris PB460 Booster Pump w/280 cleaner, Katchaleaf Cover, TF100 Test Kit, FAKE MAIN DRAIN

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    Agent99's Avatar
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    Re: pH dropping but TA isn't??!

    Let me add that I'm using Kemtek MA purchased from Home Depot. I think that is 14.5% hydrochloric acid so you can probably halve your initial numbers.
    ----Chris----
    25k IG/Spa Figure 8, 18x36, Pebble Sheen Blue Granite, Sta-Rite S8M150 Cartridge Filter, Pentair 460805 400k BTU Heater & 011018 IntelliFlo VarSpd
    Liquidator, Fafco Solar Heat, Polaris PB460 Booster Pump w/280 cleaner, Katchaleaf Cover, TF100 Test Kit, FAKE MAIN DRAIN

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    Agent99's Avatar
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    Re: pH dropping but TA isn't??!

    So I tested my water last night:

    CH is still right at 230; hasn't budged since day 3.

    TA is up to 100 from 70 although I expected it to be 90 adding almost 3 quarts of baking soda.

    pH is 7.5.

    FC is 4 ish; CC 0

    CYA is 35ish
    ----Chris----
    25k IG/Spa Figure 8, 18x36, Pebble Sheen Blue Granite, Sta-Rite S8M150 Cartridge Filter, Pentair 460805 400k BTU Heater & 011018 IntelliFlo VarSpd
    Liquidator, Fafco Solar Heat, Polaris PB460 Booster Pump w/280 cleaner, Katchaleaf Cover, TF100 Test Kit, FAKE MAIN DRAIN

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