I'm not sure of the exact temperature within the freezer, but freeze precips have worked before in it no problem. They were in there for about 20-22 hours. I agree with you though, a scale definitely needs to be used next time. I wasn't aware that DMT crystals behaved like that. So it's entirely possible that the amount of DMT actually in the pipe was minuscule? Even though it looked "the same as last time?"