+ Reply to Thread
Results 1 to 5 of 5

Thread: How much much muriatic acid do I add to lower the PH?

  1. #1
    Join Date
    Jul 2006
    Posts
    60

    Default How much much muriatic acid do I add to lower the PH?

    I just had my water tested at Leslies, but I am going to test it myself in a little while. The guys at Leslies were no help... "Do you sell anything to lower PH?"... "Uh... no..."

    Anyway my Ph is 8.0 according to them. Is that too high to swim? How much much muriatic acid do I add to lower the PH?

    Here are all of my numbers according to Leslies:

    FC 5
    PH 8.0 or higher
    TA 90
    CH 200
    CYA 50
    TDS 500


    Ed
    Thanks,
    Ed

    --------------------------
    33,000 Gallon
    20'x40'
    Vinyl
    IG
    --------------------------

  2. #2
    Watermom's Avatar
    Watermom is offline Super Moderator Quark Inspector Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars
    Join Date
    Dec 1969
    Location
    Charleston, WV
    Posts
    11,248

    Default Re: How much much muriatic acid do I add to lower the PH?

    In a pool this size, each 24 oz. of muriatic acid will lower your ph by approximately 0.2. Don't try and get the ph to your target in one shot. Better to add a few doses spaced apart with testing in between instead of one ultra big dose. Aim for 7.4-7.6. As far as can you swim .... sure.

  3. #3
    Join Date
    Jul 2006
    Posts
    60

    Default Re: How much much muriatic acid do I add to lower the PH?

    I did a test of the water myself... With the drop test kit and with a test strip... PH was below 7.0. Can the leslies numbers really be that far off? Also, is there anyway to rapidly decrease the FC? My test say the FC is > 10. My daughter's bday party is Sat. We the FC level decrease enough by then?

    Ed

    Quote Originally Posted by Watermom View Post
    In a pool this size, each 24 oz. of muriatic acid will lower your ph by approximately 0.2. Don't try and get the ph to your target in one shot. Better to add a few doses spaced apart with testing in between instead of one ultra big dose. Aim for 7.4-7.6. As far as can you swim .... sure.
    Thanks,
    Ed

    --------------------------
    33,000 Gallon
    20'x40'
    Vinyl
    IG
    --------------------------

  4. #4
    Watermom's Avatar
    Watermom is offline Super Moderator Quark Inspector Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars Watermom 4 stars
    Join Date
    Dec 1969
    Location
    Charleston, WV
    Posts
    11,248

    Default Re: How much much muriatic acid do I add to lower the PH?

    I would trust my own results over those from a pool store.

    If your FC is >10, that is pretty vague. It could mean 11 or it could mean 30 or ?? So, without having a more accurate reading, it is hard to know what your FC reading will be by Saturday. If your test kit won't read high enough for the amount of chlorine in the water, you can dilute your sample. Take one part pool water and one part distilled water, test as usual and then multiply the result by 2. If that doesn't take it high enough, take one part pool water and 2 parts distilled, then multiply by 3, etc. You do lose some accuracy the more you dilute, but it will give you a better reading than just "greater than 10."

  5. #5
    chem geek is offline PF Support Team Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
    Join Date
    Nov 2004
    Location
    California
    Age
    55
    Posts
    2,143

    Default Re: How much much muriatic acid do I add to lower the PH?

    Quoting from the Taylor "Pool & Spa Water Chemistry - A Testing & Treatment Guide", under "TESTING pH"..."FALSE READINGS:"

    high levels of chlorine (usually > 10 ppm) will quickly and completely convert phenol red into another pH indicator (chlorphenol red). This new indicator is a dark purple when the water's pH is above 6.6. Unfortunately, some pool operators mistake the purple color for dark red and think the pool water is very alkaline and wrongly add acid to the pool.

    When a sanitizer level is not extreme, only some of the phenol red may convert to chlorphenol red. However, purple + orange (for example, pH 7.4) = red. This error is more subtle as no purple color is observed and the operator does not suspect that a false high pH reading has been produced. Some operators neutralize the sanitizer first by adding a drop of chlorine neutralizer (i.e., sodium thiosulfate). However, thiosulfate solutions have a high pH and, if heavily used, may cause a false higher sample pH.


    It sounds like your high chlorine levels may have fooled your pool store into thinking you had higher pH, but I'm not sure why your test didn't have the same problem. Perhaps the chlorine level dropped somewhat between the two tests or the pool store pH test may not have any thiosulfate built into it the way that the Taylor test does (I think). I would probably trust your numbers.

    The chlorine level should drop rather quickly if you keep your pool uncovered during the day and exposed to sunlight. It may lose at least a third of its chlorine in a day this time of year (up to half during peak summer).

    Richard

+ Reply to Thread

Similar Threads

  1. Will adding cyanuric acid also lower pH?
    By Leehicks79 in forum Pool Chemicals & Pool Water Problems
    Replies: 1
    Last Post: 06-23-2013, 09:12 PM
  2. Using Muriatic Acid to Safely Lower Your Pool's pH
    By PoolDoc in forum Testing and Adjusting Pool Water Chemistry
    Replies: 18
    Last Post: 06-23-2013, 11:47 AM
  3. Aeration / Acid Treatment to lower Alk
    By Donski in forum Dealing with Alkalinity and Calcium
    Replies: 5
    Last Post: 06-27-2011, 09:17 PM
  4. Lowering TA with Dry Acid Or Muriatic Acid
    By CelticDaddio in forum Dealing with Alkalinity and Calcium
    Replies: 30
    Last Post: 07-05-2007, 12:54 AM
  5. Pool store advice to lower alkalinity - three day muriatic acid dose method
    By aquarium in forum Dealing with Alkalinity and Calcium
    Replies: 14
    Last Post: 07-03-2006, 10:04 PM

Bookmarks

Posting Permissions

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