We were 48h without power, room temperature dropped to 42-45F. I have a 4k generator, but the problems started around 3 am so initially believed Centerpoint it will be "45 min" or "just a bit over an hour", not fun to start you generator outside in the middle of the night in subfreezing temperature ... Fell back asleep around 4 am while "monitoring" the situation ... tank temps where 63-65F in 65G SW tanks and 51F in FW one. Turned out that my SW heaters, that I was normally not using, and powerful chiller that was supposed to be also a heater, were not much for this situation, so I resorted first to topping of with boiled RODI water and the second day, when even this was not enough to stop temps falling, I started to warm/boil small amounts of saltwater and dump it directly into the sump. It seem to work, I only freaked out a bit seeing that one stainless steel pot I used developed rusty spots on the bottom, but everything seems to do great, now that I gradually raised temps to 74F (my normal temps are 78-80F, but house is still just 60F). I iniatially was warming saltwater in the microwave, but it was too slow and temp in one tank dropped to 62.8F what freaked me out. Fish was acting normal, just a bit less active at 63-65F, corals and nem seemed unhappy/retracted, but definitely alive. We lost only one FW fish, probably from trying to raise he water temp too much, really bummed about it, since it was my son's favorite (and the only) fish
. But other than that, the generator was a life saver and I learned that normal heater ratings are for raising water temp no more than 10F above room temperature, definitely buying a (couple) really powerful heaters now.
Do you have any experience with rusty spots/possible iron contamination? I was planning to do (close to?) 100% water change when situation stabilizes in the next couple days. I know many people are aginst such changes, but I had good experience with them before as long as I kept temperatures matched and did not disturb the sand bed.
Sadly, I had no internet when tank temperatures fell - does anybody know what is the maximum safe temp raise per hour? I have read somewhere now it is 4F, I fought before, based on what I was reading on acclimating fish shipped in bad weather, that I can got away with much more as long as it is spread over an hour, but did not work in our case.