how much manganese is bad in a pool

[engrav]

Using well water for pool fill
In the well water manganese is .09 ppm
Is this too much? What is too much?
Searched but could not find levels, maybe I missed

 

[chem geek]

We don't have a definitive level where staining would become a problem, mostly because it's far less common than iron and copper staining. Nevertheless, according to this paper the solubility of oxidized manganese as black/brown manganese dioxide (MnO₂) is roughly 0.1 ppm Manganese at pH 7.0 and increases in solubility to 0.3 ppm at pH 8.4. This 0.1 ppm is also roughly the limit for when unoxidized manganese might precipitate as light gray manganese carbonate (MnCO₃) at high pH (8.0). The manganese dioxide can also get oxidized by chlorine to permanganate ion (MnO₄^-) which is purple in color.

So I would bet that you are OK though on the edge at 0.1 ppm but note that if you use your well water for refilling after evaporation that the manganese level could climb over time.

 

[engrav]

Thank you, got it

We have had the well water tested. I think I will scoop up some pool water and have manganese measured.

If I pay the freight for manganese I might as well add iron and copper. Should I measure any others while at it?

 

[chem geek]

For metals that can cause staining, those are the three to worry about.

 

[engrav]

For metals that can cause staining, those are the three to worry about.

thanks, got it
will order 'em up

 

[engrav]

results are back
Cu Fe and Mn are ND, not detectable; cool
but a puzzle
if the fill well water is .09 Mn how can the pool be ND Mn?

- - - Updated - - -

from the web
"Essentially, the oxidizing agent (chlorine) causes rapid oxidation or "rusting" of the dissolved iron and manganese causing it to precipitate out of the water and turn into a solid particle. The particle is then mechanically filtered out of the water."
maybe this is where the Mn went

 

[chem geek]

The oxidized manganese is still slightly soluble as I noted in my post so it shouldn't have precipitated and filtered out since you started with such a low level. If such testing were free, I'd send them a sample of your well water to see if they detect the 0.09 ppm manganese in it. At any rate, it sounds like you don't have anything to worry about.

 

[engrav]

If such testing were free, I'd send them a sample of your well water to see if they detect the 0.09 ppm manganese in it. At any rate, it sounds like you don't have anything to worry about.

Not free but not so much so will have well water re-tested.

Thank you.

 

[engrav]

Mn value in well water returned, .057
barely above established contamination level of .05
will cease thinking about metals
thank you all

 

[Swampwoman]

^ I want your well. Just sayin