heat cord runs help!

[jazii]

just setting up another tank, first time using heat cords, any idea on how many 'runs' should have, the tank is 400mmx400mm and its going to house geckos, so the sand will be 1-2inch thick with a sheet of glass on top of the cord, and needs to be about 32degrees, yes thermostat will be used but the cord is going to heat multiple tanks so im trying to get an idea of what people use.

 

[Sami-Lochy]

I use about 5/6 runs to heat my enclosure that's 60 by 40cm, the runs are packed tightly together, even touching at some points, never had any problems but. And one run goes around the whole enclosure to keep ambient temps up.