"The pump won't really hel
"The pump won't really help on an "overflow", but depending on the size of the tank you may want a pump to empty out the livewell itself.
My point is, say it's a 15 gallon livewell. That can represent 150 pounds of water (about 10 lbs/gallon) that you are hauling around with your boat.
Normally, you would just pull the plug and drain when you get back on the trailer or whatever, but I find it nice to not have to burn gas to carry the extra weight (I have twin 30 gallon wells).
It does depend on your situation, but for the cost of a pump I find it well worth it. Both my wells (on my big boat) have two pumps - one for water in and one for water out (spliced into the "gravity" drain hose so I can pump out while on the water quickly)..."