i have a homemade incubator (using a terrarium and heat mat ) and it keeps a wonderful steady temp (had it on for 5 days now and its kept the same temp the whole time with a humidity of 63%. but the temp is only 89 degrees any ideas how i can up the temp without adding an extra mat/heatlamp etc? would adding a 'substrate' maybe help or making fake walls out of polystyrene blocks so the space to heat up is smaller? any ideas greatfull recieved. i have 7 months to perfect it for next years chicks..but would like to get it sorted before then for a trila run if possible!