I can't get my TA to go down.

Haley

0
LifeTime Supporter
Jun 30, 2013
73
Washington
Hi all,

For the last week, I've been trying to get my TA down by lowering my pH (which likes to creep up by about 1ppm every day). My pH has been around 7.4-7.6, so I add enough muriatic acid daily to bring it down to 7.0 but my TA remains anywhere from 140-160. :brickwall:

I don't have any leaks, my other numbers look great... any ideas? :suspect:
 
By the way, I just went to check what the percentages were for the chemical make-up of the muriatic acid and here's what the box said:

KEMTEK Muriatic Acid- For pool and spa care (purchased at Home Depot)
Principal Functioning Agent:
Hydrogen Chloride...14.50%
Constituents Ineffective as a spray adjuvant...85.50%
TOTAL...100%
 
Hi JohnN and Faby3003, :wave:

To answer questions:

1. I've added a total of about 1/2 a gallon over the last 4 days. I read on TFP that I should target 7.1 and maybe add a little less to see how the pool reacts, so I've been cautiously adding and testing daily.

2. I have not added any new pool water since the first fill about a week ago. In fact, my numbers on the first day of my fill were: TA-140 and pH- 7.3.

3. "Have you ever tested the pH and TA of your fill water?" I did the first day of my fill, and like I said, I haven't put any new fill water in. I can test from the hose if you think that would help?

After reading more, I know this is a slow process with the TA lowering. Am I just being too impatient? :hammer: I do need to fill the pool today a couple of inches. The kids have been splashing around and it needs to be replenished. :snorkle:
 
If you look at Effects of adding chemicals in http://www.poolcalculator.com/, you can plug in the acid dose (by the way, you know you're getting the weak stuff, right?) and see what it will do to the TA.

As an aside, why are you actively lowering it? Do you have high CH and you want to prevent scaling? Or are you having to add acid every day and you're sick of it and want to get ahead? Because TA in itself is not harmful.
 
According to the pool calculator, adding 64oz. of 15.7% muriatic acid (close to the 14.5% you have) will lower the TA by 28ppm. So, you should be seeing a drop.

I'm assuming you're testing the TA yourself? Below are the extended test kit instructions for TA. I've found that wiping the bottle with a wet cloth between adding drops does make a difference in my results.

One last thing, if you don't have a SWG, you don't have to worry about high TA. You really only need to add acid when your pH gets as high as 7.8. Anything 7.8 or below is no problem.

TA - Total Alkalinity


Rinse the sample tube with pool water.
Fill the sample tube with pool water to the 25 ml mark. The top of the sample will be curved. This curve is called a meniscus. The bottom of the meniscus should be level with the 25 ml mark.
Add 2 drops of R-0007 and swirl to mix.
Add 5 drops of R-0008 and swirl to mix. The solution should turn green or blue. If the sample turns red, pink, or yellow, you are done, your TA is zero, and your PH is very very low.
Counting the number of drops as you go, add R-0009 one drop at a time, swirling to mix after each drop.
Continue adding drops until the color changes to something more or less red, pink, yellow, or clear. The sample may switch between green, blue, and gray while you are adding drops. That is not the color change you are waiting for.

Continue adding drops as long as the color continues changing. The final drop, that does not change the color any further, does not count.

Multiply the number of drops by 10 to get your TA level. Remember that the final drop, which didn't cause any further color change, doesn't count.
Dispose of the sample safely. It is best to pour it down the drain with the water running. Do not add it back to the pool.
Rinse the sample tube with tap water and store for next time.

Notes

Sometimes a static electric charge can build up on the R-0009 dropper bottle tip, causing the drops to be smaller than usual and making the test read higher than actual. You can prevent this by wipping the tip of the dropper bottle with a damp cloth or tissue before you start and after each drop.
Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
If you expect that your TA level is extremely high, you can do the test so that each drop is 25, instead of 10, to speed up the process and save on reagent usage. Use 10 ml of pool water, 1 drop of R-0007, 3 drops of R-0008, and multiply the number of drops of R-0009 by 25 to get your TA level.
R-0007 is thiosulfate, used to neutralize chlorine so it won't interfere with the test. Extra R-0007 can be added when the FC level is very high to help prevent the dye from bleaching out.
R-0008 is total alkalinity indicator, an organic dye used to provide the green/red color. It should be a dark green color. If the dye stains the plastic bottle it is stored in, it has gone bad.
R-0009 is sulfuric acid, used to titrate until the color changes.
The precision of the measurement is plus or minus one drop when up to 10 drops of titrant are used, or plus or minus 10% of the final reading, when more than 10 drops of titrant are used.
 
Hi Richard and Faby3003,

Richard, yeah I knew it was the weaker one, but that was all Home Depot had. No, I don't have high CH (and I have vinyl anyway) so I guess I'm just trying to do what Pool School says and get my numbers within range. Isn't that what a good little TFP girl does?? :angel:


Faby, I see daily a drop in my numbers but then it goes up a little the next day. We had like a SPLASH of rain 2 days ago, but seriously, it rained for like 10 minutes- not too heavy. I do the test very carefully. I wipe each bottle- it's a tricky test! You really gotta watch for that color change, subtract the last drop when the color doesn't shift any further... :stirpot:


It looks like I don't need to worry too much about it. I don't have SWG and I have a vinyl pool; in the meantime I'll focus on my pH and hopefully it will slooooowly adjust.

Thank you SO MUCH for your help! It really is great to be able to bounce my dismay off the TFP. :lovetfp:
 
If you let the pH drift up to 7.8 before adjusting, hopefully you'll find you only need to add acid a couple of times a week instead of every day.

It is pretty sweet once you get your TA into that 70-90 range. My TA has been at 80 all season, and I haven't had to adjust my pH once.
 

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