I try and keep my Taylor K2006 kit in a cool, dark, dry place but the Florida heat and humidity seems to have got the better of my DPD powder (not original, replacement from tftestkits). It's black and very clumpy. That shouldn't be a problem in itself, but this stuff sticks to the side of the measuring cylinder in spots. The FC test works fine, but I'm left with a spotty residue in the tube that will not remove come off or dissolve easily. I have to soak in bleach and scrub the tube to get it clean again.
It would be a shame to throw half a pot away, unless anyone knows a good removal chemical? I'll be putting an order in tomorrow whatever.