Well, I tried water, though not drums full because of door size and I do have a crushed rock floor. Our climate is very unpredictable in these days of change, but two winters ago we were back down to -22F (-30C) and we have gotten to -32F. This year we only came close to 0F. Electricity is quite expensive here so I can't afford a heater that would run 24/7. Ventilation and mold are also a problem with the cold air. Thanks Colleen in NE Calif. -----Original Message----- From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of Alberto Castillo Sent: Sunday, June 10, 2012 1:58 PM To: Pacific Bulb Society Subject: Re: [pbs] New book Colleen, not even a lean-to one? You have the black painted water filled drums resource, that is excellent, also a crushed rock pit instead of floors, etc.