Can peromonosulphate drastically reduce ph?

[pflood4150]

Can peromonosulphate drastically reduce ph? I ask this as my spa ph dropped off the scale and chloring readings were at zero despite have ing been added daily.

 

[JamesW]

What chlorine do you use and how much has been added?

What is the TA?

https://www.uww.edu/riskmanagement/msds/data/oxone_monopersulfate_compound_du_pont_chemicals_6.10.93.pdf

https://www.horizonpoolsupply.com/_uls/resources/SDS--Oxone-Monopersulfate-Non-Chlorine-Shock.pdf

https://sts.gr/wp-content/uploads/2012/04/Powerful_Oxidation_G1.pdf

 

[JamesW]

MPS is net-acidic when added to the water (lowers pH). Bleach will initially raise pH because it contains excess lye from the manufacturing process but that pH rise should be lowered over time as bromine chemical reactions are acidic. Your tablets are also acidic as well which is why you pH is going down.

If you plan to use tablets then you need to monitor pH and TA closely and add back alkalinity (using baking soda) as the TA decreases. Baking soda will also slowly raise pH as carbon dioxide outgases from the tub.

 

[JamesW]

The product is acidic on addition, but basic as it oxidizes things.

The product is 23% Potassium bisulfate, which is dry acid (pH down).

If it oxidizes something like bromide to bromine or a metal like iron, then the net reaction is basic.

If it oxidizes something like ammonia that has a lot of hydrogen ions, then it can be net acidic.

Trichlor and dichlor are usually net acidic.

If you are ever surprised by the test results, that generally indicates that you are not testing the water enough.

Can you provide some history for the test results including all numbers and all chemicals added?

 

[JamesW]

2KHSO₅ + 4e^- + KHSO₄ + K₂SO₄ --> 5K⁺ + H₂O + OH^- + 4SO₄^2-.

The two oxygen atoms each get one electron and you get sulfate with an oxygen atom in the -2 state being released.

The reaction releases 2 oxygen atoms and 3 hydrogen atoms, which is net basic.

It looks like the reaction comes out slightly basic, so it depends on exactly what you are oxidizing.

The two oxygen atoms go from -1 to -2, which is similar to how hydrogen peroxide works.

Ammonia will be mostly Ammonium, which is NH₄⁺, which releases a 4 hydrogen per molecule.

 

[JamesW]

6KHSO₅ + 4NH₄⁺ + 3KHSO₄ + 3K₂SO₄ --> 15K⁺ + 2N₂ + 6H₂O + 13H⁺ + 12SO₄^2-.

So, when oxidizing ammonia, the net reaction is acidic.

 

[JamesW]

The product creates a lot of sulfate, which is generally best to avoid.