I am trying to figure out how many gallons per hour I would need for a tank. Honestly a formula I could use for any tank would be nice but right now I'm looking for one for a 40G tank and a 15G tank.

I have a small filter that I am planning on running on the 15G tank. I doesn't say the GPH only the Volts, is there a conversion of volts to gallons per hour?

The plan is substitute some of the power I would need from pumps with the filter (not even planning for put a media in the filter because I'm solely using it for move water)

Also I have a bubble pump thingy that I don't use in my FW tank, would it be a good idea to put in a SW tank or no?

Thank you