black gunk in speedstir beaker

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agnathra

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May 6, 2015
20
Chattanooga
hey everyone, thanks in advance for your help (again!)!

so i've been using the tftest 100 with a speedstir for the last several weeks. about a week ago, i noticed black stuff in the test cylinder i use for chlorine. it looks like mold or something on it. i didn't worry about it.

but now it's gotten harder to see the results of chlorine tests, almost like the pink tinge never completely goes away. but i put more drops in and it never gets clearer...everything just seems kind of gray. so i try to clean the cylinder.

so that stuff, i can't really wipe it off. and then why i try to wash it off with soap, it really starts smearing, like it's grease. so i try to bleach it off, and that doesn't seem to help. the speedstir pellet/capsule thing had a bunch on it, but i cleaned it almost totally off, just wiping.

so then i use a clean cylinder with the speedstir, and i swear after it spins a while, it looks like there is more gunk on the new cylinder than was on the outside of the pellet.

so i'm just wondering, is there anything in this pellet that could leak out? or if this is just some kind of mold, will it affect the tests?

thanks!
 
I had that happen earlier this year and just used a very small bit of MA to fill inside of the tube with the bean in it, pouring the MA into the pool and rinsing it out good. It just seemed like the DPD powder was adhearing to the bottom, but the testing was still accurate.

These days when I test I grab a paper towel and use it during testing and then use it to dry out the tube after use.
 
thanks for the response. i think you're right about the DPD powder. i got things very clean and tried the test again and had black smears everywhere.

and as for the test itself, i could never get the water sample totally clear. it always stayed a slightly pinkish gray. Now as i added drops, the color would lighten to a point, but then never completely clear. and the reading at the lightest point matched my taylor test kit...so i think the chems are working, just so messy that it's hard to read (or trust the results).

i'm just going to throw out these reagents and buy some more...and keep the new ones in the house. i think the heat/humidity is what messed things up.

thanks!
 
i'm just going to throw out these reagents and buy some more...and keep the new ones in the house. i think the heat/humidity is what messed things up.
Click to expand...

Always best to keep the test kit in a climate controlled environment. It will definitely help keep the reagents fresher longer. My kit is in the laundry room cabinet. While it may be a little more humid in there than the rest of the house - humidity is a relative thing here in AZ - it is cool in there. Presently the inside humidity is about 20% - only 11% outside.

LOL - I guess humidity is a relative thing everywhere. :cool:
 
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