I've used inexpensive bilge pumps from Walmart or Sears and a 12V relay. http://www.walmart.com/ip/Shoreline-Bilge-Pump/16609596 http://www.walmart.com/ip/Shor

I've used inexpensive bilge pumps from Walmart or Sears and a 12V relay. http://www.walmart.com/ip/Shoreline-Bilge-Pump/16609596 http://www.walmart.com/ip/Shoreline-Bilge-Pump/16609596 These start at $13 for 600 GPH. Then use a 5V relay to switch the 12V relay. http://www.radioshack.com/product/index.jsp?productId=2062480 http://www.radioshack.com/product/index.jsp?productId=206248... http://www.radioshack.com/product/index.jsp?productId=12466792&retainProdsInSession=1 http://www.radioshack.com/product/index.jsp?productId=124667... YMMV.