Bartier Disinfection Index

[chem geek]

Also, my understanding of MPS is that it will not break down chloramines....

I can understand the benifits of MPS with an indoor pool but the caveat seems to be that a residual of MPS is required in the water at all times for them to be effective in the prevention of the formation of chloramines. I see no real advantage to their use in outdoor pools.

Yikes! I had no idea that MPS didn't oxidize monochloramine, but the Dupont literature certainly implies that MPS only prevents their formation. Ben told me that supercholorination to achieve breakpoint almost never works, especially for indoor pools with poor air circulation. He speculated that sunlight breaks down monochloramines in outdoor pools and I've read literature that suggests the same thing.

So this begs the question of how do you get rid of monochloramines? If a pool has CYA in it, then you need a heck of a lot of chlorine to properly shock it. Originally I was thinking that a small amount of CYA for indoor pools was a good idea to reduce effective chlorine concentrations to minimize exposure to bathers (and their swimsuits), but that would make superchlorination even more difficult. A real catch-22. Why wouldn't you use a constant level of MPS to prevent monochloramine formation? Is this not necessary in outdoor pools due to the breakdown from sunlight?

(NOTE: I have contacted Dupont to ask them if their MSP product, Oxone, will oxidize monochloramine in which case it could be used as a shock and not just as a chloramine preventative. I will let you know their response, if any.)