Muriatic Acid

[TomC]

Hi All,

Well, we have used up all our PH minus and have now switched to muriatic acid to try and lower our pH. Since we are new to muriatic acid, we have no idea how much to start with.

The pH is up around 8.0, the TA is approximately 100ppm, the tub is 418 gallons. I a cup of muriatic acid too much to try?

Thanks in advance. We do know that this stuff is very caustic and we will be careful ;o)

Thanks...Tom

[DubyaB]

Too much. Go to the pool calculator to find out your amount I think more like 1-2 oz is all you need.

[TomC]

Too much. Go to the pool calculator to find out your amount I think more like 1-2 oz is all you need.

Hi Dubya,

With the pool calculator, what does "Goal:Not Setup" mean?

Thanks...Tom

[DubyaB]

Hi Tom

At the bottom. You need to fill out the boxes to let the spreadsheet know what your using for chlorine/what your spa surface is etc.

Warren

[TomC]

Hi,

On a similar topic, is it critical to wait a certain amount of time before doing a pH test? We have been adding muriatic acid, waiting 20mins, and then testing. Is that an ok process?

Thanks...Tom

[mcw53]

Well, we have used up all our PH minus and have now switched to muriatic acid to try and lower our pH. Since we are new to muriatic acid, we have no idea how much to start with.

The pH is up around 8.0, the TA is approximately 100ppm, the tub is 418 gallons. I a cup of muriatic acid too much to try?

With the pool calculator, what does "Goal:Not Setup" mean?

According to the pool calculator, you would need 0.4 ounces of 31.45% muratic acid to lower pH from 8.0 to 7.6. You don't need to set up a goal to use the calculator. Enter your spa size, current values (FC, pH, TA, Borates, CYA, etc) in the left column and target values in the right column.

[TomC]

Well, we have used up all our PH minus and have now switched to muriatic acid to try and lower our pH. Since we are new to muriatic acid, we have no idea how much to start with.

The pH is up around 8.0, the TA is approximately 100ppm, the tub is 418 gallons. I a cup of muriatic acid too much to try?

With the pool calculator, what does "Goal:Not Setup" mean?

According to the pool calculator, you would need 0.4 ounces of 31.45% muratic acid to lower pH from 8.0 to 7.6. You don't need to set up a goal to use the calculator. Enter your spa size, current values (FC, pH, TA, Borates, CYA, etc) in the left column and target values in the right column.

Hey Mike,

Thanks, the real life example helped!!!

Tom

[Maxemily]

My experience with muratic acid and my 325 gal. tub tells me .4 oz will not do enough for you in the long run. Your PH might initially drop to 7.6, but it will climb again in short order.

A better approach might be to drop TA in increments and see where PH stabilizes.

If you look at the bottom of the Pool Calculator page you will find an 'Effects of adding chemicals' paragraph. This app. contradicts the calculator section somewhat in that it shows a .57 drop in PH with 1 oz of muratic acid added to your tub. The TA drop looks accurate for you and that is where I would focus, if I were you.

Add the oz., check TA to confirm drop accuracy, then check PH and PH again tomorrow. Keep this pattern up until your PH stays where you want it.

For what it's worth, my tub likes: TA 60, CH 200, CYA 25, Borates 50, Temp 100. This gives me a saturation index of -0.14 but keeps my PH rock solid at 7.6

[OttawaGreg]

Hi All,

Well, we have used up all our PH minus and have now switched to muriatic acid to try and lower our pH. Since we are new to muriatic acid, we have no idea how much to start with.

The pH is up around 8.0, the TA is approximately 100ppm, the tub is 418 gallons. I a cup of muriatic acid too much to try?

Thanks in advance. We do know that this stuff is very caustic and we will be careful ;o)

Thanks...Tom

Tom,

I used 2tbsp (30 ml) in my 280 gallon tub to take the pH from 8.0 -> 7.5 (roughly). So minus 0.5 of the pH.

Hope this helps. BTW, measure and add the acid to a plastic container over the sink that is filled with say a cup or two of tap water. You don't want to spill this (un-diluted) on anything.

Greg

[PaulR]

Acid will drop both the pH and TA, check out this link:

Lowering Total Alkalinity

In the Pool Calculator, the top section will tell you how much acid you need based on your current pH and TA. The 'Effects of adding chemicals' section does not take your TA into account when telling you what will happen. So, they can give different results. Your best bet for normal use is to fill in all your current info in the top section, and then plug in your target pH and see what it says to do.

--paulr