i know tom touched on this, but from what ive heard there's more to be said. an email correspondance from Ron Newman (creator of this site :
http://www.focuser.com/atm/anodize/anodize99.html) had this to say about temp.
(NOT MY WORDS CASWELL)
OK I'm going to tell you why I don't think Detecting PAR during anodizing using low current will work well when doing med/large sized parts. I think it is a great way when anodizing very small parts with minimal heat generated into the bath during anodizing. However as soon as larger parts are done the heat generated into the acid bath changes the impedance of the whole system messing up any reading one could make with a meter. How can one detect a very slight impedance change (PAR) if the system as a whole changes due to a few degrees of heat building up in the solution.
Impedance will go down when the temp goes up causing no detection of PAR when it should occur and be detected.
I think LCD can work well if the acid tank is large enough to absorb the energy to the point where it does not raise the acid temp more then a degree duriing the run.
Detecting PAR would be easier with all variables the same.
Again, im not dissing caswell at all, they've done alot of work and research, but there are those that have legitimate points that would disagree.