New chlorine powder test question .....

TizMe

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Aug 26, 2007
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#1
Not sure if this is the right category or not But Dave I have a question about the new chlorine test powder I receive lately...

I have a little bit of the old chlorine test powder left over can I mix it with the new stuff I just got. Are you using a new powder as well this year I noticed right away this stuff is white and the other I had was purple in color?
 

duraleigh

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Apr 1, 2007
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#2
I would not mix it. As the powder (R-870) gets older, it darkens. IMO, this happens from exposure to relative humidity.

I have some powder that I have been using that is 4+ years old and I still get apparently good test results but, is it as good as the new we get in? Probably not. We get it in in large containers and it is a very light gray. Once opened it starts to darken in the container and will continue to darken anytime it is not in an air tight container. My 4 year old stuff is almost charcoal and quite clumpy.

My point is it is obviously undergoing a change of some sort and while apparently harmless, if I really need to know my FC precisely and confidantly, I use the new stuff.

Taylor says to replace it every year. I cannot dispute that statement but I think most of the chems can go longer than that. Just how long is an answer I don't know so I think you should err on the safe side.

Use your old stuff when the accuracy is not critical and keep your new seperate to insure it's viability.

Incidentally, Some of you have asked why the R-0871 liquid comes in an opaque bottle......it's light sensitive. Do not leave it outside for any length of time....even in the container....it will soon become ineffective.
 
G
#3
DPD powder darkens and looses potency as it oxidized from atmosphereic oxygen in the presence of moisture, much in the same way an open bottle of permanent hair color will turn dark and lose potency (which is no surprise because DPD and other phenylenediamines are the dye bases in permanent hair color!)