test kits/tubes and stoppers

[kveeti]

I just recently started using AP test kits and I like them. But I hate the stoppers. I hold the lids down as tight as possible, but they still leak. The liquid gets between the lid and the tube sides. When I’m doing the kh and gh tests, for example, this accumulation splashes a bit each time I take the lids off. At the end of the test (I’m going to 6 drops) the total water level in the tube (although adding extra liquid with the drops) is below the 5 mL line. This can’t be good. Never mind shaking the nitrate test for 1 minute - I have to wrap paper towels around the tubes.

Rona (like a Home Hardware) has cheap little rubber stoppers that are wonderful. I bought one and want to buy a whole slew of them for replacement lids.

Then I got to wondering if rubber will absorb anything and would that, in turn, or the rubber itself screw up the tests? I found this statement online “Natural rubber does not age as well as many of the synthetics nor is it as chemically inert as some. It is inferior to many of the synthetics for heat aging, resistance to sunlight, oxygen, ozone, solvents or oils.” I don’t know if the little rubber stoppers are ‘natural’ rubber, I threw out the package, but I think it just said rubber.

Does anybody else experience the leaking, is it just me, do you do anything about it, any other solutions. (???)

 

[CatLover]

I use those test tubes. Mine leak, but I just wrap a paper towel around it while I shake it.

 

[pl*co]

Mine leak, especially because if I'm not careful when I lift the cap off, a piece of the plastic tube snaps off and sticks in the cap. On the other hand, the glass tubes that come with, have plastic caps that fit tight. It's just that I tend to be clumsy and will probably drop and break the tubes in the sink or something. Otherwise, I'd use them instead. A piece of plastic wrap over the top of the plastic tube prior to putting the cap on might help.