Maintaining Free Chlorine!

[Chad]

MPS must oxidize the whole thing because when I shock when I have 1ppm CC, I don't suddenly have an extra 1ppm FC in my water after the shock but I'm certainly no chemist either.

[svspa]

Good point drewstar.

Bill,

How often are you using that MPS?

I missed one thing in your first email. You said that CC is still zero the next day.

You would think if the FC was being used up killing something the CC reading would go up as your FC reading goes down. Unless MPS was introduced to oxidize the CC (that wouldn't necessarily effect the TC or FC readings).

So another question would be did you shock with MPS before you took your chlorine readings on the second day?

A general routine would be to manage your dichlor on a daily (roughly) basis, for example 1-3ppm like your dealer said. Then shocking about once a week, or when combined chlorines get high.

Shocking is designed to oxidize contaminants (oils, etc.) and combined chlorines.

Since you said you had 10ppm FC I assumed you were shocking with dichlor, that amount sounds like a shock dose.

If you are also adding MPS it could explain why you might see anomalies in your chlorine readings. MPS will oxidize the CC out, but could have a marginal impact on the FC and TC, giving you that FC=TC reading.  

You should use either dichlor or MPS for your weekly shock,but not both at the same time. I am using MPS to shock weekly and about monthly I substitute dichlor for my shock so the tub gets super sanitized because of the higher dichlor dose.

Or everything I said could be wrong, there are so many variables when dealing with this stuff that we can just give you some general guidelines and things to consider.

Steve

[hottubdan]

Should one expect to get a boost to fc readings after shocking with MPS?  When the MPS chemically reacts with the contaminants, does it oxidize just the contaminant that is attached or "combined" with the chlorine molecule thereby "freeing" up the chlorine molecule to combine again or does it oxidize the entire chlorine/contaminant molecule/particle?  I was under the impression that it would oxidize the entire thing...but, like others have mentioned, I'm no chemist...although I did stay at a Holiday Inn Express last night...

BTW, we certainly would expect an increase in fc when shocking with dichlor...pretty obvious but I felt it worth mentioning in this context.

With chlorine we oxidize everything.  With bromine we free up the bromine molecule, recreating hypobromous acid.

[ZzTop]

Another route is to use a floater using chlorine pucks.  The floater must be adjusted to allow a very small residual amount to enter the water.   Once properly adjusted you will always have a low level of chlorine in your water.
This relieves the need to worry about checking the chlorine level daily and if you do not use your tub for a few days or a week or two there will always be some chlorine in you water.  
regards Zz

[tony]

Another route is to use a floater using chlorine pucks.  The floater must be adjusted to allow a very small residual amount to enter the water.   Once properly adjusted you will always have a low level of chlorine in your water.
This relieves the need to worry about checking the chlorine level daily and if you do not use your tub for a few days or a week or two there will always be some chlorine in you water.  
regards Zz

Don't use chlorine pucks in a Caldera spa.  It may void warranty.  If you want to use pucks in a floater, use bromine.