Ring around the CL test tube?

[Gooserider]

I have noticed that over the month or two that I've been using my TF100 test kit that I'm developing a ring around the Cl Only plastic vial that is used for the FAS / DPD test. It is a cloudiness or frosted look from about the 10ml line, up to around the 20 - 30ml line, where it slowly fades out, which I would say roughly matches the area that would be intermittently covered while swirling the test to mix between drops. The area below the 10ml line, where the test water itself sits is still clear.

I've tried gently scrubbing at it, and it doesn't seem to come off. It seems like the plastic is getting etched a bit. I rinse the vial before and after each test w/ pool water, and let it air dry in between tests.

The only real problem it causes is the frosting seems to make the water sit unevenly in the tube, making it a bit hard to read the meniscus to see what the water level is. As a result I'm guessing that my water volume for the test is only good to + / - about 0.5ml - not sure if it makes a difference.

1. What is the cause of this?

2. Is it normal?

3. Does it pose any problem for future testing, if so what needs to be done about it?

Thanks,
Gooserider

 

[Guest]

You are not cleaning the vial out propery. In the future wipe it out with a paper towel after rinsing it. If it is buildup from oxidized DPD (which eventually turns dark) you can pour some bleach in the vial and let it sit for an hour or two and then rinse THOROUGHLY and wipe out the vial. This often helps. If it is scale deposit you can rinse the via with an acidic solution to remove it, perhaps some very diluted muriatic acid or some white vinegar. Let this solution sit for an hour or so, rinse out the vial and wipe it. DO NOT MIX THE ACID WITH THE BLEACH!

 

[mickey4paws]

Mmm....I have the same problem. I do try to wipe it down with a paper towel after use, but I guess I didn't do a good enough job. I'll try the vinegar soak first to see if that helps. What about CLR (for using to clean coffee pot deposits)? Would that be okay to use?

 

[Gooserider]

Well, I tried a several hour soak w/ white vinegar, it might be a little better, but is still mostly there...

Will try bleach and possibly some other solvents to see if any of them help. (one at a time of course, I know enough not to mix chemistries...)

I had deliberately NOT been wiping out the vial on the theory that air drying after rinsing would minimize the effects of any contamination, but will try wiping it in the future.

Gooserider

 

[Guest]

Hmm, I say to use bleach first (implied it at least) and then try vinegar and two people do the vinegar. I said to try the bleach first since it is usually more effective since the "haze" is usually from the DPD powder.

 

[Gooserider]

Hmm, I say to use bleach first (implied it at least) and then try vinegar and two people do the vinegar. I said to try the bleach first since it is usually more effective since the "haze" is usually from the DPD powder.

Didn't read that way to me, but no biggie... I tried the vinegar first just because it was easiest / handiest - I test in the kitchen, and the vinegar is right there, and in a small, easy to dispense container. The bleach I'd have to go out to the pool area and try to figure out how to dispense a small quantity from the 5 gallon carboy... Not a huge deal, but...

Gooserider

 

[Guest]

No Clorox in the laundry room?

 

[Gooserider]

No Clorox in the laundry room?

Not sure, haven't checked - the laundry room is almost as far from the testing kit as the pool... However today I took the vial out to the pool w/ me and scooped some 12.5% up after pouring it into my measuring container to dump in the pool... It's been soaking for a couple hours now, so I just rinsed it out, looks pretty clean now...

Gooserider

 

[Guest]

Cool! Now I get to say I told you so!