Monopersulphate use

[jrenwick]

I was told Monopersulphate would give me false highs on my cc, but in fact my fc rose 1.0ppm??????

Any reason anyone can think for this? I have ordered the Deox reagent to neutralize for testing , but that will take a day or 2.

We used to use Oxone, never had this happen, used a new company (the old one folded) the chemical ingredient listed is exactly the same.

Our chlorine tabs and prominent system are very stable, I cannot see any reason it would have jumped up over night 1.0ppm fc and has stayed there for the last 9 hours. I have used 3 different reagent kits all still good with dates.

any help is appreciated!!!

 

[JoyfulNoise]

Monopersulfate interferes with the titrating reagent, R-0871, as it is a reducing agent (ferrous ammonium sulfate). So when chlorine is present along with MPS, it takes more drops of R-0871 to change the pink color to clear. Thus it will look like your FC levels are higher.

The only time that MPS will affect the CC measurement is if the FC is zero and then you add the R-0003 potassium iodide reagent. MPS will oxidize the iodide to triiodide and then that will create more of the oxidized DPD dye (stronger pink color). Then it will take more drops of R-0871 to go from pink to clear giving the false impression that CCs are higher.

If you plan to use MPS often, then you need to have the deoxidizer reagent to get an accurate measure of FC and CC.

 

[jrenwick]

Thank you,that is great! I was told only the CC would be elevated (more drops) and could not figure out why the FC was high. I have already ordered the deoxidizer reagent for next time. We usually use it once a month, but our previous supplier folded so it was from a new company, same chemical.
Really appreciate the input, don't really have anyone to ask!