It sounds like the first true set of leaves hasn't even come in yet. Keep them under the flouros. I usually wait till they have about 4 sets of leaves and a nice little root system, sometimes 2-3 weeks. I've always had more problems than good things come from rushing mother nature. In the mean time you might want to get a cheap heating pad instead so you can set the dail and keep it constant since you are throwing your money away on hydro costs using your hps, in the long run the heating pad would save you money. As for the temp spike just ride it out and make sure it doesn't happen again, that's all you can do.