Just my 2c worth on this, 25C is an Autumn day's temp and they will be in hibernation deep under ground by now! Today we are in Autumn in South Africa and it is about 31 C outside, Summer days in a pan will get up to high 30's and 40's. I would disagree with using a heating pad if you are going to put it under the tank as they are a burrowing species and if the heat comes from below it may cook the lil critter. I have no experience keeping them (BIG criminal offence to keep them here cause they are a TOPS species so MEGA fine!!!!!) but from my observations of being in the field is the temps are high but they should also have a cool place to burrow in. Don't forget even Highveld summer nights are in the high 20's C... trust me we had this in Jan and Feb and no airconditioning made it a nightmare