Rick/Ray-
I have one heat-mat I could use, but six InnTainers. I could try and install the 25W aqua heaters. I'd then have 25Wx6= 150W max power running. The oil-filled heater I just purchased runs at 1500W max and probably around 800-900W on low setting. I'm hoping to find a way to setup a timer where the heater runs when the temps start to fall below 60F. I don't want the nighttime temps much below 58F (55F is the official mark), but I also want to keep those temps no higher than 70F at night. It sounds like 70-85F is ideal for daytime, but I'll probably just let the temps hang around the 65-70F that the lights keep the area at naturally, maybe augmenting a little here and there with that heater.
In any case, I through out a less efficient ceramic heater last night and was able to keep the farthest Tainer (at soil surface) above 60F (but below 70F). Downside: had to run it on low power setting (900W for around 8-hours). Since I'm up to 3rd tier here, that cost me $.15*8*0.9 = $1.08. I'm hoping to bring that down to below $.50, better yet $.25 a day with the oil-filled heater.
Thanks,
Naysen
http://gardening.about.com/od/proble...lossomDrop.htm