[deltatechx]

Is there something I can add to water that will change it's color at certain temps (around 22c to 45c).  The research I've done has only yielded Leuco Dyes, but I can't find any info on using them in solution and can't find anywhere online selling them.  What I'm looking for is something that will change from clear to red at about 33c, but any solution (non toxic preferred) that changes color around that temp would be a good start.

Thanks