Overshock with MPS - Is it Possible?

[Sudzz]

Just curious.  I tend to shock the tub once a week with a non-chlorine shock and then add chlorine after each use or every other day - whichever comes first.  Just before a shock, I can tell it's needed because the chlorine levels drop  a little quicker than just after a shock.

Is it possible to over-shock?  My method of measurement for the shock is pretty inaccurate since I tend to just use the cap from the container.  I also like to shock it just before and after a heavy use when some friends come by to keep the water as clear as possible.  If I don't shock this way, the water can cloud up a bit and sometimes takes twice as much shock to "bring it back".

I can't see any harm in doing it so I was just curious what other, more experienced folks might think.

[Chad]

Any mps that is remaining after it oxidizes all the chloramines(CC), remains in the water until more organics are introduced to the water. Then it starts oxidizing again.

The reason you're noticing your FC level dropping faster towards the end of the week is b/c your chlorine is now being used for both sanitizing and oxidizing. Where earlier in the week the "over dose" of mps from the previous week's shock was taking care of the oxidizing. Which is what mps is best at, preventing the formation of chloramines. It will help rid them but it's primary purpose is to prevent the organics(amonia) from forming with the chlorine - creating combined chlorine and thus allows the chlorine to work more efficently as a sanitizer.

[BauerN]

Sudzz,

At the doses & usage you're describing, I don't see a major cause for concern.  Have had customers with high volume usage (usually parents of teenagers) use MPS the same way you just explained, never a complaint.

I don't think I'd recommend too large of a dose, especially if you're using the spa relatively soon after.  MPS reacts with organics, and at high levels will probably irritate the skin at least.

[Jacuzzi Jim]

I think shocking before use is kind  of a waste, I know there are quite a few people that do, when I shock, it will always be after use, or just once a week if not less.

[tony]

As Chad mentioned, one of the advantages to shocking with mps vs chlorine is if you add too little or too much mps, there is no harm done.  It is a bit more fool proof than chlorine where you must reach breakpoint chlorination to get the desired effect.  If you add too little mps, it will oxidize as much as it can and there will be no residual.   if you add too much mps, it will oxidize everything available and retain a residual which will wait for something more to oxidize.

[tinybubbles]

This thread made me think.  Most people either use MPS or dichlor after soaking (or before).  Would there be any logic to someone adding both at the same time?  Things that make you go, hmmmm.

[windsurfdog]

This thread made me think.  Most people either use MPS or dichlor after soaking (or before).  Would there be any logic to someone adding both at the same time?  Things that make you go, hmmmm.

I'm sure it could be done without harm but I don't think "the juice would be worth the squeeze".  Better, IMO, to stick with dichlor after the soak and a good shock, either dichlor or MPS, whenever CC levels have elevated or on a regular weekly to bi-weekly schedule.  BTW, don't forget that MPS elevates TDS quicker...another good reason to avoid daily MPS introductions.  YMMV... 8-)