Okay, so my ambient temp and cool side temp is 28c. Im using a Habistat Digital Thermostat (http://www.scalesandfangs.co.uk/heat...-digital-range).
The heat mat is 7w and is 6" by 11" (http://www.scalesandfangs.co.uk/heat...m-6x11-7-watts). Temps have increased 2 or 3 degrees since adding the bubble wrap around the tank, but I wish I knew why I have to set the thermostat so high ? My room temps are cold however (66f) and I suppose this word affect tank temps.
Thanks everyone for your help.