Muriatic acid and phosphates

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gorocket1981

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Jun 8, 2018
163
Montreal, Canada
Hello,

I got Muriatic acid to lower ph as recommended. On the container it says stop the pump for 12 hours after putting the acid in the pool. Is that normal? Are you doing this that way? It seems weird.

And what about phosphates? Pool store said I have 322 and want me to buy a high price stuff to lower it. What is the truth with that?
 
Pour the acid into the return stream in a pencil size stream. Leave the pump running for at least 30 minutes after adding. Brush the area if you have a concern. That is silly what the container states.

Phosphates are algae food. With no algae, who cares? Also, even if there is a need to mess with phosphates, any level below 2500 ppb is not significant.
 
Phosphate will not be removed by chlorine. There are proper phosphate removers available, but not at pool stores. And not necessary except in very specific situations.
 
Phosphates don't go away, but they are nothing to worry about. Especially 300 ppb, that's pretty low. Even for those who choose this extra preventative step it's not worth thinking about until around 1000 ppb.

The acid instructions sound similar to some really old and outdated procedures that manage to keep sticking around. Ignore them, dose with the pump running and keep it running at least a half hour to mix everything.
 
The turn off the pump idea is based on the "Slug" method where you add the acid in a column and let it stay concentrated in a small area.

The idea has been thoroughly discredited. It's dangerous and ineffective.

Even the people who came up with the idea have acknowledged that it doesn't work.
 
JamesW said:
The turn off the pump idea is based on the "Slug" method where you add the acid in a column and let it stay concentrated in a small area.

The idea has been thoroughly discredited. It's dangerous and ineffective.

Even the people who came up with the idea have acknowledged that it doesn't work.
Click to expand...

Just for the sake of curiosity, could you explain their theory? What were they hoping to accomplish?
 
Rollercoastr said:
Just for the sake of curiosity, could you explain their theory? What were they hoping to accomplish?
Click to expand...

Acid column myth

Here is a link to a paper on the myth of lowering TA by the 'slug' or acid column method. Interesting reading!
www.troublefreepool.com www.troublefreepool.com
 

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Rollercoastr said:
The website has removed the articles. It seems the theory was about a lowering TA with a particular method of pouring MA?
Click to expand...
Ha! So they have -- probably because the method is quite dangerous.
It was a method to lower TA, that resulted in damaged pool surfaces.
 
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Oh OK. Clearly, directions should be updated.

Another weird thing, the pool store told me that muriatic acid was not good to lower pH as it was also lowering alcalinity. When I said that dry acid was also lowering alcalinity, he said no. I asked him to explain why and how that was possible. No answer...
 
watershapes.com

Exploring the 'Acid Column' - Water Shapes

People who believe that the way acid is added to a pool can differentially affect water chemistry are wrong, writes Kim Skinner -- and here's a detailed look at the science that backs him up.
watershapes.com watershapes.com

Here is a source still promoting the method.

Lowering Total Alkalinity
To reduce excess alkalinity in the pool, one must slug the acid as opposed to feeding it through a chemical feeder or spreading the acid as you would do to lower the pH of the water. To slug the acid means to add the acid at three or four columns around the pool. This procedure concentrates the acid in the column thereby lowering the total alkalinity in that immediate area.
Total alkalinity is not appreciably reduced until the pH of a small volume of water is
lowered to the 4 to 6 pH range. The alkalinity is removed from the column of water and allowed to mix with the remainder of the pool water to give an overall lowering effect.
By carrying out this procedure at different locations around the pool, the total alkalinity will be significantly reduced. The amount of acid to be used for this purpose can be determined by the table in Appendix C (1).
Procedures for Slugging the Acid
Remember: Never slug acid in a pool when it is open to the public!
1. Turn off the recirculation system.
2. Always add acid to two or three locations in the deepest portion of the
pool in a slow, careful manner so that acid does not lie on the pool bottom. To prevent damage to the pool bottom, slugging should not be done in the shallow end of the pool.
3. Never over treat with acid.
Click to expand...

Again, it's nonsense based on false science.

Muriatic acid is the best chemical to lower pH or alkalinity.

Use PoolMath to calculate the Effects of adding chemicals in the bottom section titled Effects of adding chemicals.

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.
www.troublefreepool.com
 
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