no, do NOT water. remember rarely do plants die from underwatering, & u KNOW it doesnt need it, u said so urself; trust ur instinct! BRAVO for using the best watering method=water by weight. Those temps r very low for daytime. 78 is ideally what they like but they can tolerate a range of temps, but yes that can cause ur plant to slow uptake of water as it doesnt need that much. next time when u know ur temps r going to run that low, simply water less at each watering, instead of all the way through till u can pick up the temps or they r later...like in flowering where there uptake of water increases dramatically. imo its not cold enough to call for a heater. r u using fans on them? this should expedite the drying as well & make sure the air circulation up & around the top of the pot stays fresh. a bit sickly? u would have to post pics for further recommendations.