hello i have a 650gm female that hasnt been eating very well and always stays on the coolest part of the tank. she is in a 40 gal. breeder i have heat cord taped on 2/3 of the bottom of the tank and a 75 watt light on the top. the warm side stays between 90 and 85 and the cool side gets down to about 75 in the corners and thats where she stays. is this normal?