APC 2200 XL with an extra battery, will be able to run a Mag18 for approximately 9 hours (100W draw = 11.5 hrs and 200W draw = 6.5 hrs / mag 18 is rated at 145W),
http://www.apc.com/resource/include...ily=Smart%2D
UPS plus I can daisy chain extra batteries onto it up to 10 total. 9 extra batteries would run the pump approximately 100 hours... I was originally going to get an APC 3000 net but after talking to a person who sells battery back ups he explained to me that the 2200XL would be better for my use. The XL models are meant for long run time and all of the wiring is much heavier gauge as well as the unit is designed for it.
You can get them over Ebay for around $200-$500 depending on how many extra batteries they have.
I have an APC Matrix 3000 on my system running a Mag18, after 3 hrs of running the battery was still at 67%. Although the housing and wiring is different, the 2200XL and the matrix 3000 use the same batteries inside of the battery cases so the run times are basically the same with the same load. With 3 extra batteries you should be able to get about 24hrs of run time on the pump, not sure how much effect the heater would have on the run time. HTH
I'm not sure that this is the answer that you were looking for but... during outages here, I normally hand my wife a long handle wooden spoon and a long straw. That way you take care of the circulation problem, the aeration, and you can still sit back and enjoy the tank by candle light. I know, I know... your wife and I are no longer friends are we ? Let me know if you need some spoons, always glad to help.
