shocking to remove DBPs

[Beez]

Hello all,

I know the company line is that shocking is not necessary for a well maintained pool, but wouldn't occasional shocks be beneficial to eradicate disinfection by products, or will a properly maintained FC take care of that?

Thanks,
Dave

 

[reebok]

what is a disinfection byproduct?
to answer my own question, I believe CC's are what happens when chlorine attaches and kills an invader. it is an "intermediate breakdown product" according to pool school.
as I understand it, all pools have CC's because the chlorine is breaking stuff down. it's just usually a very very small amount. this would be why kids (or whoever) get red eyes after swimming for hours - CC exposure even though you may not be able to measure the level of CC's.

 

[Beez]

what is a disinfection byproduct?

Well, that is possibly an implied question within my original post. I know that many of them as CCs are burned off with normal FC levels, but aren't there more insidious chemical byproducts that are generated in a chlorinated pool? I confess I am a victim of health related newsletters and websites that throw out scare tactic propaganda that may not be reliable...

 

[Guest]

They are not a problem in outdoor pools since they are mostly broken down by UV and/or are volatile and gas off. They are a problem in indoor pools not exposed to UV and that do not have good air handlers, particularly when there is NO CYA present.
Normal FC levels normally take care of them in outdoor pools. If you have them they will show up as CC.

I confess I am a victim of health related newsletters and websites that throw out scare tactic propaganda that may not be reliable...

A little bit of fact mixed with some omission of facts and misinformation from these "Health" websites leads to this type of confusion. Once you get the facts it all becomes much clearer. I bet not one of them mentioned that this is primarily a problem in indoor pools with poor air handlers.

 

[Beez]

They are not a problem in outdoor pools since they are mostly broken down by UV and/or are volatile and gas off. They are a problem in indoor pools not exposed to UV and that do not have good air handlers, particularly when there is NO CYA present.
Normal FC levels normally take care of them in outdoor pools. If you have them they will show up as CC.

I confess I am a victim of health related newsletters and websites that throw out scare tactic propaganda that may not be reliable...

A little bit of fact mixed with some omission of facts and misinformation from these "Health" websites leads to this type of confusion. Once you get the facts it all becomes much clearer. I bet not one of them mentioned that this is primarily a problem in indoor pools with poor air handlers.
Of course not! That's not in the manual "How to Bilk a Fortune from Unsuspecting Consumers"

Thanks for that waterbear! It has been a nagging question in the back of my mind ever since I got the pool.

 

[chem geek]

Just remember that shocking does nothing more than increase the concentration of chlorine, so this would increase the chemical reaction rate for any reactions in which chlorine participates. That's all. There isn't any "magic" level at which point all of a sudden things start to happen. It's simply a continuum.

The concept of "breakpoint" chlorination is when you are adding chlorine to water that already has ammonia in it -- in this situation, the chlorine reactions go in steps so there is, in this case, a "magic" amount of chlorine when things all of a sudden change. This is not the situation in pools, however, since you already have chlorine in the water and are instead introducing smaller amounts of ammonia (and mostly urea) into it. In other words, you already have chlorine amounts well beyond the "breakpoint" level.

For the chlorine reaction with ammonia, the production of very irritating nitrogen trichloride is actually higher in both peak and total cumulative amounts at higher chlorine levels so in this case shocking actually creates MORE of this irritating chemical (technical details about this are here). The only time you'd need to more regularly shock is under conditions of high bather loads where the amounts of introduced contaminants to the water is at a rather high rate so you need to accelerate the reactions to stay caught up, but in this situation there are other solutions possible to assist in oxidation on a more continual basis, including ozone and UV, but again this are not needed in typical residential pools (and even most commercial/public pools are able to get by without such supplementation, especially if they are outdoor pools as waterbear described).

Richard