Has anyone done any research or does anyone just know if different substrates conduct heat differently? Let me explain . . . over the last 1 1/2 years we have moved from newspaper, to mulch and now recently to aspen. We did not change the heat setting of our Helix or Herpstat II, neither did we change the position of the heat cable. However, when we check the temps in the tubs with the aspen, it seems to be lower than it was with the newspaper and the mulch.

Now I know that humidity is impacted significantly with different substrates - mulch holds moisture when new and thus has a higher humidity than aspen or newspapers. But I didn't realize that there could be a different tub temp with the different types of substrates.

With the probe placed on the heat source, if different substrates do conduct heat (or insulate as the case may be) differently, does it seem reasonable that we would need to adjust the thermostat to get the temps in the tub equal to what we need for a BP?

I would appreciate hearing form anyone who has experience with this situation. Thanks everyone for all you on-going help and encouragement!