This mini pump really sucks!
(from vendor webpage-reverse psychology marketing I guess)
There is a brand new special high tech device you might consider using : it's called a FUSE.
http://www.radioshack.com/product/index.jsp?productId=2102786
If the ac/dc adaptor is plugged into ac and the output is dc , with an inline fuse (we still don't know the pump current rating so you'll have to measure it to choose the fuse value=> (operating current +30%).