Returning to something from the first thread.
About blowing bubbles to pump water from the bottom to the surface,
so natural aereation can occure.
Low power needs.
A pic is worth a million words.
http://www.quantumlynx.com/water/back/vol2no2/v22_st5.html
THATS what I was talking about!
Your purpose (other than fun) is just to move the water around with low power made by the overflow, so you only need a discharge head of an inch.
For the question you are going to ask next-
No, I can't figure out how to run a fish tank bubble maker from 12v DC. Not with any efficiency at least.
The question after that-
Those little battery pumps, like from the pet store or sporting good shops, only last about 100 hours and the plastic cams wear out.
Even the expensive ones.
Just in case-
Windshield washer pumps only run a minute or so pumping air (burn up with no cooling I think)
And they burn up pumping water continiously in just a few minutes too.
Hope my many years of very extensive experiance in the broad field of burning up perfectly good brand new expensive things saves you some time, money, and frustration!!!
(that means I know more about what won't work, than what will)
G-