I followed your suggestion and tried this, using some 17W pads that raise the bottom temp about 10°-20° over ambient, and it is quite remarkable how the plants respond.
From what I've seen so far, it's not the absolute temperature that makes the difference, just that teh root zone is warmer - or am I fooling myself?
What I really think it is that even when the temp drops at night the area that has bottom heat stays warm throught the root zone and even around the plants like a little sphere to its self.
I put the probe of a digital thermo 4" up in the pot (root Zone) and on the surface of the pot for a few days every time I looked theyy were within a half a degree.
The new PA works better than the other leca's I've tried three besides PA. The others dry out pretty rapidly with bottom heat you have to constantly moisten the surface of the pot.
Ive been doing a little prep on the Pa like you suggested soaking 48 hrs man it really does make a difference there are no floaters after 36 hours.
I'll just keep on playing glad you tried it did you use your o-2 yet that will impress even you they really get going then.
Ray, I don't think you are fooling yourself. You know what causes spring. It is, of course the sun warming the soil, thus telling the plants it is time to grow.