Well, I made it thru a pretty good ice storm, and even a 2 day power outage without losing any fish surprisingly enough. My 90 acrylic held temp for an amazing 20 hours (blanketed) before dropping significantly. It never dropped below 73 though. My small 10 got down to 68, and with frequent warm water additions, they pulled through as well. I believe I put both thru a mini cycle when I changed all filter media after power came on. My amonia is .25 and no3 are @ 0. Aside from frequent pwc, is there anything else I need to do? It would be a shame to lose any fish now...TIA, Farmgirl