A few more Bromine related questions

[fmanji]

1. I can't really figure out why I have to add shock every week if I'm having no problem maintaining a residual bromine level of 3-6ppm, i.e. is there some way of definitively knowing when or if you have to shock the spa if everything seems okay.

2. When you shock, can the floater stay in the tub or must it be removed?

 

[chem geek]

Your floater is probably dissolving enough bromine at a rate where you don't need to shock. Yes, you can leave the floater in when you shock -- the chlorine or MPS will mostly react with the bromide in the bulk water to from more bromine.

 

[Guest]

The main reason to shock a bromine system is to destroy bromamines. While bromamines are effective sanitizers they do contribute the 'fishy' smell that is one of the objectionalbe disadvantages of bromine. Also, you still need to shock a spa because of the high bather to water ratio since so many organics build up in the water so fast.

 

[fmanji]

But I don't quite understand why I need to shock if there is always a good amount of residual bromine, wont this bromine oxidize the organics? What will shocking do that the residual bromine can't do?

 

[chem geek]

waterbear is saying that bromine can combine with ammonia and other substances to from bromamine or essentially "combined bromine" and that this could build up and not get oxidized as readily by bromine alone. If that happens, then shocking the water with chlorine or MPS can get rid of the bromamine. I suppose you could just see how it goes and if your water develops any smells or dullness that would tell you that shocking was necessary.

In a chlorine spa maintained with sufficient chlorine, shocking isn't typically necessary, similar to a pool. I was assuming that bromine could deal with getting rid of bromamine, but that isn't necessarily the case and I was wrong to assume that.

 

[fmanji]

Waterbear, can you confirm that one needs to shock a Bromine spa to get rid of bromamines and other organics, that 4-6ppm of Free Bromine is insufficient, and still needs regular shocking to 20ppm?

 

[Guest]

Waterbear, can you confirm that one needs to shock a Bromine spa to get rid of bromamines and other organics, that 4-6ppm of Free Bromine is insufficient, and still needs regular shocking to 20ppm?

I thought I already did in my post above. 4-6 ppm hypobromous acid (free bromine) is about the same as 2-3 ppm hypochlorous acid which we know is not enough to destroy chloramines even with no CYA.
Also, most bromine tests are for total bromine and not free bromine. Total bromine is going to be higher in just about all cases, sometimes by several ppm so you are actually testing the bromamine level.

It's your spa and if you don't want to shock it weekly so be it. Bromamines are sanitizers, they just have a fishy odor that most people find objectionable. Also, because of the high bather to water ratio in a pool compared to a spa ALL spas (not just bromine) will benefit by weekly shocking to destroy organics. With a chlorine spa we see this from the chloramines that form but we do not test separately for bromamines in a bromine spa.

 

[fmanji]

Thanks for clarifying, I just had to make sure as what you said conflicted with what chem geek said about not having to shock.

I also thought that bromamines have little to no odour, so was not expecting a "fishy" smell...

So shock weekly to 20ppm to destroy bromamines produced by combining with organics, as those are the ones that are ineffective as a sanitizer, and produce a fishy smell, correct?

Thanks, hopefully this will help other people as well to understand why shocking is still necessary when using Bromine, as we are led to believe that all Bromamines have disinfecting capabilities, and very little odour, but this seems to be an oversimplification.

 

[JasonLion]

So shock weekly to 20ppm to destroy bromamines produced by combining with organics, as those are the ones that are ineffective as a sanitizer, and produce a fishy smell, correct?

As waterbear said in his previous post: bromamines are sanitizers, they just smell bad.

 

[Guest]

Thanks for clarifying, I just had to make sure as what you said conflicted with what chem geek said about not having to shock.

I very rarely disagree with Richard and when I do it is usually because he is approaching a problem from a theoretical point of view and I interject real life observations. Neither is really 'wrong' and when taken together the answer is often 'exactly right'. For this very reason we often PM back and forth to brainstorm on different issues of pool and spa care and we have been doing this for longer than this particular forum has existed!
In any spa, because of the high bather to water ratio, shociking on a regular basis (or continuous application of ozone in a chlorine spa) is needed to oxidize organics, IMHO.
The same would not be necessary in a pool.
It's all about the organic load in a given volume of water.

Since I do not know what post of Richard's you are referring to nor did you provide a link I really cannot comment on why or why not he said that shocking was not needed.

 

[fmanji]

Okay thanks, FWIW I've been using the Bromine system as outlined in TFP by Waterbear, I don't think I would be this far this fast without this forum. So it has been a terriffic learning experience

I was just trying to understand better and maybe even provide a few learning's from a newbie.

 

[chem geek]

I can't really comment intelligently about the need for shocking in a bromine spa since bromine may take longer to oxidize organics, especially when much of the bromine may in the form of bromamine yet you are not knowing that because it all registers as Total Bromine in the bromine tests. I would completely and totally follow Evan's (waterbear's) advice on this.

I do believe that in a chlorine spa if one uses a sufficiently high level of chlorine for the bather load and has a reasonable CYA level, that the need for shocking is minimal and usually not needed. For every person-hour of soaking in a hot (100-104F) spa, it takes around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of MPS non-chlorine shock to oxidize the bather waste. Of course, the easiest way to know if enough chlorine is being used is if you get a reasonable (> 1 ppm FC, more is better) chlorine residual before the next soak.

It's true that the bather load is very high in a spa, but the hot water temperatures seem to make all the reaction rates go a lot faster and also make the chlorine more "active" in that less gets bound to CYA. So while I would agree that with Dichlor-only users a shock may be needed when the CYA level gets higher (after a month it's not unusual for the CYA to be > 100 ppm), I'm not so sure the same would be true for those using the Dichlor-then-bleach method where the CYA is kept at around 30 ppm or so. Those spas seems to maintain good water quality for a long time even if there is no shocking -- so long as sufficient chlorine is used. Many people simply don't use enough chlorine and that, of course, can be offset by making up for the deficit by shocking.

Of course, only time and reported experiences of many spa users will tell whether what I've just laid out is reasonable or not.

Richard

 

[okstpat]

I have seen the ref to "bather load" as every person soaking in a hot (100-104f) spa, but what if the temp is 90-99f?

 

[chem geek]

You may find that the amount of needed sanitizer/oxidizer is little bit less if you soak at lower temperatures, but you really need to test your sanitizer level and adjust accordingly. The rule-of-thumb is just that -- it's not an absolute formula to follow. It's just a starting point until you determine your tub's actual sanitizer/oxidizer demand. Also note that an ozonator generally lowers such demand if one soaks every day or two or for bromine spas.