Bleach vs MPS


Aug 18, 2015
Is one better than the other to use as and oxidizer after soaks and for weekly shocking? Bleach is definatley cheaper but my spa manual says in big bold letters not to use it, but I see tons of people on here do. Other than the fact that the chemical and spa companies loose out when you use bleach, what other reason would there be to avoid it? Is it somehow more unsafe than other shocks or damaging to the tub? Chlorine is chlorine right?

BTW I use the spa frog system and add small amount of MPS after every soak and do a stronger shock once a week.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
The reason that the spa manuals say not to use bleach is that using bleach with no CYA in the water has the chlorine be far too strong. They are talking about chlorine spas. So the right way to use bleach is with the Dichlor-then-bleach method or to otherwise get CYA in the water. For a bromine spa, this doesn't matter since the chlorine will very rapidly oxidize bromide from your initially added sodium bromide (plus any bromide spent from the bromine tabs) to create bromine.

MPS is slower to oxidize bromine so it will hang around a bit oxidizing some bather waste. Some people find they need to shock on occasion with chlorine to keep the water clear, especially if they have no ozonator. So I'd say it's really up to you with whatever seems to be working well. You could initially use some Dichlor as your chlorine source to build up some CYA if you were concerned that you used up your bromide bank so were really a chlorine spa (it's hard to know the difference, though bromine does smell somewhat different than chlorine).
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