...so thanks to the replies to this thread, I think the problem of low humidity at night has been solved. *I normally keep the plants raised off of the floor of the terrarium with clear, inverted cups in order to get the plants right under the lights. *I simply added 1/2" of distilled water to the bottom of the tank. *If I seal the terrarium at night after adding the frozen bottle, temp drops to 57 degrees with a humidity of 90-92%. *Apparently, the large surface area of water available for evaporation at the bottom of the tank simply keeps the humidity high despite condensation on the bottle of ice. *Oh, and the lids on the hamatas are now open in the morning! * [img]http://www.**********.com/iB_html/non-cgi/emoticons/smile.gif[/img] *Thanks again for the helpful replies.