Quote: QUESTION I would like to run both fans off of one single cord but want to check with those more knowledgeable about electrical requirements. Please forgive me if this is incorrect, but I know was of the understanding that one of the measurements for capacity (watts, volts, or amps) is not a measure of the total allowed, but more of a maximum for each individual item. Is that this amps? If so, then it should be fine to run 2 12 amp fans off one 13 amp cord, correct?
I think what you need is this:
Voltage has to match on fans and power supply. 110AC if you want to plug into a wall outlet, etc. I find I like it much better to keep 110Ac away from the tanks when practical. Another factor will be noise. I would suggest one computer fan will run very quiet with less heating and do the job well. So I would go looking for a 12VDC computer fan and then try to find a 12VDC power supply. These may be found in your junk box or a trip to Goodwill might turn one up for a couple dollars. Plug in wall-wart like for charging phones etc?
For a 12VDC fan-- match the 12VDC. anything else on the power supply voltage is not likely to work.
The other important point to match is the output power rating. Aps for large stuff but likely to be rated in milliamps (MA) for small stuff like these fans. Two fans, just add the ratings of each fan together. Make sure the power supply is MORE than the fans require. Lots more is not a problem other than as the power supply rating gets bigger, the unit may get too large (expensive?)
A fan like this in 12VDC might be nice and have the filter available as well. Fry's are not good about listing things like the voltage. But if they were 12VDC using 50Ma then you want a power supply putting out 12VDC and rated 50MA or 100MA for two fans-- at least.
Power supply putting out 1000MA ( equal to 1 amp!) would be able to run 20 fans.
I also would say you need a way in as out for good air movement. But one fan should do it easy.
Unless you get really, really big fans in 110AC the cord size will not be a problem. But your example of two fans at 12 amp will burn out a 13 amp cord. Just that a 12 amp fan may be four feet across??? Amps are big things when speaking of this type fan.