Actually its more a case of your filters many lose their prime when the power goes out and need to be reprimed, others just won't work with a battery because the sine wave(electrical) is not the same. Your best plan would be an air pump thats battery backed up with a sponge filter running -Anne
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There can never be to many bichir creature keepers
darn more money to spend
oh well time to go shopping for my little friends and my soon to get friends after new tank is setup and cycled
another question: i been hearing alot about this uv sterilizer and diatom thing what do they do and what do they look like so i can find them and buy one or the other
UV - look on www.bigalsonline.com - you can get the same one I ordered (check my sig)
As far as battery backup goes, you can get units at a computer store that would work that are designed to keep computers running in the case of a power outtage. They are really expensive though, I would just get a battery powered air pump (also at Big Al's) for less than $10 if you are worried.
Are you going to use a canister filter? You should if you are getting a UV, otherwise you will have to get a pump also to send the water through. I would get the same one I have even though you only have a 40g, because the smaller ones are not much cheaper and in the case of UV, more is better. It is basically silent.
I would say either return your current filter and get a canister (I think with a 40g you can use the Fluval 204, which is pretty cheap) or keep it and skip the UV. Canister filters are really nice, they filter really well and are really quiet.
You can get power inverters at auto supplies that bump 12 v up to 115 volts. The come in different wattages. You would need to figure out what size to get by checking your equipment. volts X Amps = watts. Get one twice as big as calculated for extended use. Run time will depend on load and how many batteries you have.