Effects of very low PH

[Patflemming]

My hot tub had a very high PH reading after an extended vacation, so I added some easy acid. Next morning my water had a yellow tinge, and the PH was extremely low. I quickly added baking soda and now I'm.in the normal range. My question is: how much damage can very low PH water do in roughly 12 hrs?

 

[ajw22]

None

 

[mas985]

With a yellow tint, I would assume a PH around 6.8 which is not very corrosive.

The next time something like that occurs, skip the baking soda and just turn on the spa jets and PH should rise fairly quickly.

 

[Patflemming]

Thanks for the reassurance. Just for personal learning, what other tint color could corrosive water be?

 

[mas985]

Thanks for the reassurance. Just for personal learning, what other tint color could corrosive water be?

I have an acid dosing system and based upon dilution tables for HCL, the PH of the solution should be around 0 and here is what PH test of that solution would look like:


You might think it actually falls between 7.0 and 6.8 but it is well below 6.8. You just can't trust the test below PH 6.8.

Also there is not really a specific PH level where all of a sudden, water becomes corrosive. It is a sliding scale. The lower the PH the more corrosive and the less time that is required for corrosion to occur.

This chart shows the corrosion rate for iron. Note how slow it is for PH above 4.0.

Corrosion of iron

This chart is very telling and it shows some comparison to other common liquids:



This chart is for pump material selection:

pH value pump material selection | BBA Pumps

The pH value is an international scale, ranging from 0 to 14 which indicates the acidity of a liquid. This value is an important factor to consider when selecting the right pump. The acidity of the liquid determines the corrosion reaction of the material and therefore the service life of the...

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