75 is alright for the cool side. Sounds like you have enough animals that a tempgun might be a good investment. Its hard to give an opinion on the wattage without an exact temp. Are either of them spending time on the warm side? You can always use the old fashioned rule of thumb, if they spend all the time on the cool side, its too hot, all the time on the warm side, it's too cold. You could try the infrared, do you have any heat on them at night?
