"unless the fish already had ich, and the tank was never fallow, and the fish were never treated properly, there is no way for the fish to get ich."
Not true. Many, many, many people experience ich outbreaks as a result of spikes in temperature. For the most part, the ich parasite is present in every single tank we own....period. The 'outbreaks' occur when the 'fish are not treated properly' as you do suggest....such as a spike in temperature. The ich parasite can lay dormant in substrates, live rock, etc. and in general is present in every reef tank. Again, the 'outbreaks' occur when the fish lose their slime coat and therefore are no longer resistant to the attachent of the parasite while it is in it's free-swimming phase. Additionally, the spike in temperature dramatically stimulates the growth and reproduction of the parasite, which can result in a huge population of free-swimming parasties looking for a nice warm body to attach to. Kind of the same way that you can stimulate the reproductive cycle of many organisms (aquatic and not) with drops in temperature for a given time, followed by a relatively rapid increase in temperature.
Bottom line is that a drop in temperature, followed by a relatively rapid increase in temperature, does indeed produce the perfect conditions for an ich outbreak in ANY tank....regardless of the animal husbandry the reef owner has provided. Obviously, the healthier the tank, the less likely it is that the outbreak will be devastating, or that the parasites will even attach. Additionally, there are a lot of things we do in higher-tech reef tanks that additionally reduce the probability of catastrophic ich infestation...such as (obviously) UV steralizers, aggressive protein skimming, reef conditions that are less tolerated by parasites, and the addition of reef additives that can serve as a deterrent to the reproductive cycle of the parasite.
I hope you don't find this argumentative. I don't intend that at all. It's just I've seen MANY people fall victim to their supposition that they are not susceptible to ich (or amyloodinium) outbreaks because their tank is 'healthy' and they practice fantastic husbandry. I hate for people to learn the hard way. Again...sorry if this sounded that way.
Anyway, hope you found the cause of your short circuits and get it resolved. Also hope your fish and corals are doing well.
Best of luck and God bless.....