Well depending on where on Marc's site an which configuration he's using, he may be OK. Need more info to accurately troubleshoot.
Here's what I used...only 3 watts...seems to work great so far and cheap too.
The below site had the best specs on it...but I bought mine with the switch so it was a little more expensive.
http://www.aquatichouse.com/Pumps_files/aqualifter.asp
TOM AQUA LIFTER SUCTION PUMP
By Oscar Enterprises
This unique one-of-a-kind vacuum pump is designed to lift water with its diaphragm and flappers. There are many applications for this pump: drip system for reptile terrariums, watering device for chameleons and small frogs, circulating pump, water falls and dosing pumps for reef additives.
3 watt.
0.22l/m Volume
30" pressure.
#11371 - Aqua Lifter Pump ~ $10.