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Thread: test results, how fast can you add muriatic acid

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    fordsbyjay's Avatar
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    test results, how fast can you add muriatic acid

    I started to post this in another thread then decided to start a new thread because of multiple questions.

    How fast can you add Muriatic acid? I have been told 3 different things from the same Leslies so i don't know what to believe. I have been trying to get everything balanced out so I can switch to SWG but my results keep jumping around. I did a search here and checked the pool school but could not find an answer to my question.

    I will post the last few test results from Leslies.

    Aug 31 pool had algae starting.
    FC 3
    TC
    PH 7.4
    TA 250
    CH 120
    CYA 100
    Phospates 100
    added 3 gal of acid over two days. added 15 lbs of hardness plus

    sept 02 pool had algae over entire floor.
    FC 1
    TC 3
    PH 7.0
    TA 80
    CH 150
    CYA 100
    Phospates 100
    shocked pool with 1 gal bleach then 7 lbs of shock (it is what I had left) the next day to kill algae.

    sept 07
    FC 4
    PH 7.6
    TA 190
    CH 150
    CYA 90
    Phospates 0
    I added 1/2 gal of acid last night

    sept 8
    FC 5
    PH 7.2
    TA 150
    CH 240
    CYA 100
    Phospates 100

    The pool is clear but I have a stain (comes off with vitamin C). I am trying to get the TA 100 so I can add some stain remover.

    My two questions are:

    How fast can I add acid?

    And one more question about the CYA. They tell me to drain a foot and add water to get the CYA down. Why is this the last thing to always do because when I add the water it seems to throw my balance off again? It seems like this should be the first thing to do then balance the new water.

    Thanks,
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    dmanb2b's Avatar
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    Re: test results, how fast can you add muriatic acid

    I wouldn;t worry about acid for now...with a TA of 150, it's not urgent. What I'm more concerned about is your relatively low levels of FC as compared to your CYA level as well as the presence of CC's...what is your current CC level? I see a FC of 5, but no TC?

    For a CYA level of 100, your minimum FC should be 7 with a target of 12ppm FC.

    Your first goal should be to add more bleach to raise up that FC level and then do a partial drain and fill to lower your CYA concentration. After that is all said and done, you can lower your TA to start using a SWG.

    Good luck
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: test results, how fast can you add muriatic acid

    Although I have a dog in the fight, I would encourage you to get your own test kit and stop bouncing back and forth to Leslie's. No one will test more accurately than you and a lot of your inconsistencies will disappear.

    Do not overlook the advice to get your chlorine up....you are way too low. Check out the CYA/FC chart in Pool School.

    Do not add any acid to your pool unless you plan on aerating to lower TA (I'd leave it alone)
    Dave S. - Forum owner
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    Re: test results, how fast can you add muriatic acid

    Looking at the chlorine/cya chart I can see your point. I would be lying if I said I wasn't a little confused though. Wouldn't it make more sense to lower the CYA to 70 or 80 so that my FC only needs to be 5 instead of raising the FC then lowering the CYA which would effectively make my FC to high then?????
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    Quote Originally Posted by duraleigh
    Although I have a dog in the fight, I would encourage you to get your own test kit and stop bouncing back and forth to Leslie's. No one will test more accurately than you and a lot of your inconsistencies will disappear.
    I was thinking the same thing so I signed up as a contributor here and I am going to order my TF100 kit next.

    Do not add any acid to your pool unless you plan on aerating to lower TA (I'd leave it alone)
    I was trying to lower the TA to the recommended level for the stain remover.
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    Quote Originally Posted by fordsbyjay
    Wouldn't it make more sense to lower the CYA to 70 or 80 so that my FC only needs to be 5 instead of raising the FC then lowering the CYA which would effectively make my FC to high then?????
    Yes if you can quickly get it accomplished..like in the next 24 hrs. Otherwise the reason I suggest getting more chlorine in there first is that you want to hold off any intruding algae outbreak until you lower your CYA.

    Even at a CYA level of 70, your FC target is 8ppm
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: test results, how fast can you add muriatic acid

    I second dman's post about getting some more chlorine in there now until you can get adjusted. Putting in a small jug of clorox in the evening is an easy, adequate way of accomplishing this.

    Then......

    1. I would leave the CYA alone. If you're at 90, your close to SWG values of 60-80 so just let it come on down thru rainwater and spashout. Besides, partial draining is a hassle...as you know.

    2. Refer to the manually chlorinated chart of FC/CYA relationship until you actually have the SWG up and running. Then you can let FC drift down to the suggested levels for SWG's

    3. Do you have reason to suspect there is iron or copper in your pool? The AA test is pretty good but, IMO, not completely definitive. Did you do a test for iron or copper at Leslies (The TF-100 doesn't have those tests)

    Post back that answer and perhaps you can hold off that stain treatment for a while and try something a little easier.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: test results, how fast can you add muriatic acid

    Well that makes sense.

    I do not have a reason to think there is copper/iron in the pool and leslies never tested for it. I have several large stains on the bottom of the pool that I tested with a vitamin C tablet and it comes right off with the VC.
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    I have several large stains on the bottom of the pool that I tested with a vitamin C tablet and it comes right off with the VC.
    Did your fill water come from a well? That would indicate iron and the AA treatment is in order.

    If you filled from city water, my suspicion is the stains may be organic. Test them by holding a tri-chlor puck up against them or some granular chlorine if you have that. If the chlorine really lightens the stain or removes it, then we can treat for arganic stains by simply elevating the chlorine levels for a period of time.

    Anyway, I would suggest a slighty more positive identification of the stain and then proceed from there.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: test results, how fast can you add muriatic acid

    Quote Originally Posted by duraleigh
    and the AA treatment is in order.
    Absorbic Acid treatment right? Not the other AA

    Just kidding Dave...sounded funny when I read it quickly
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: test results, how fast can you add muriatic acid

    The water comes from the city. I am going to have my water tested at a different pool place in the morning. I thought the vitamin c was a test to determine if it was organic or not because the vitamin C is Absorbic acid....... or so I though.
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    Vitamin C (ascorbic acid) is to test for the presence of iron in your water. I suspect your test may have been faulty in some way or, in fact, AA may reduce or lighten some organic stains as well.

    Let's see what an iron test yields.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    frustratedpoolmom's Avatar
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    Re: test results, how fast can you add muriatic acid

    But if the stain is iron, and it has deposited on the pool surface, often the iron test will come up negative because it has already deposited. Once the stain is removed via AA, then the iron goes back in solution and the pool might test postive then - but I don't think an Iron test now would yield answers.... If it is iron - I would wait until your swim season is done and the temps have cooled so you don't risk algae (I didn't check where you live) before you begin the process. If it is organic, then a chlorine tablet would have the same results as you saw with the VIt C, the stain would fade - if it's iron the trichlor tablet won't do anything to it.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
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    Re: test results, how fast can you add muriatic acid

    Can anyone tell me what range of measurement the TF100 has for Chlorine? My wife had the water tested today and leslies could not measure the PH or the FAC/TAC because it was outside of their scale. They did not find anything in the iron test.

    BTW, results from another pool place were

    FAC 7.2
    TAC 7.4
    ph 6.8
    TA 120
    CH 200
    Cyanuric Acid 90
    Phosphates 200

    I am currently clear, circulating and aerating to get my PH back up.
    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    The FAS-DPD test for Free Chlorine/CCs (powder turns the sample pink, you count drops till it clears) tests FC/CC up to 50ppm.

    The OTO test for Total Chlorine (drops that turn the sample yellow) tests up to 5.
    Both tests are included in the TF100

    Leslie's is probably using a regular DPD test which only goes up to 5.

    In the future you shouldn't use so much acid to drop the PH that low in the future, try not to go below 7.0.

    Try the trichlor tablet on the stains to see if they are organic. If it does nothing, when the time is right you can proceed with the AA treatment, but as I said I would wait till the temps cool or you risk an algae bloom (the AA treatment calls for the chlorine levels to be near zero).
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: test results, how fast can you add muriatic acid

    Quote Originally Posted by frustratedpoolmom

    Leslie's is probably using a regular DPD test which only goes up to 5.
    No kidding.


    In the future you shouldn't use so much acid to drop the PH that low in the future, try not to go below 7.0.
    I was aiming for 7 and I guess I over shot it a little. I am going to aerate for a day and see what happens with the PH. BTW,

    I added two pounds of stain eliminator by Haviland from a different Pool store. We have always had good luck with it and sure enough the stain was gone 5 minutes after I added the stain remover.

    Below is a couple pics of my aerator[sp]. I tee'd into my booster pump and added a garden hose fitting. Then I just added a garden hose/fire hose nozzle and aimed it at the pool. Cost was about 10 bucks.



    19000 gallon inground fiberglass pool
    Hayward Pro Series Sand filter S244T 62 gal/min
    Whisper Flow WFE-2 / 011511 1/2 hspr pump
    Aqua Rite AQR Pro SWG, T15 cell for 25000 gal

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    Re: test results, how fast can you add muriatic acid

    Excellent Aerator! I doubt your ph will be low for long
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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