For my chlorine drop test, my 0870 reagent appears to have got damp somehow. It is dark colored, although not solidified. I did have some dry reagent left, and when I do the test they seem to yield the same results so I am guessing it is OK to use?
Second question is, for whatever reason my test tube I use for the chlorine drop test, is turning black on the inside after I run a few tests,. I am able to pour vinegar in it and clean it up but I don't remember doing that before. What causes the black residue inside the plastic tube? It is not easy to remove with just water, vinegar does remove it.
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