Pond vacuum?

Sorry if this is a beat to death question!

We have a small pond in the backyard - about 12' x 5' - it was here when we
bought the house 8 years ago. There is now much sludge on the bottom, most
likely due to my poor pond-keeping habits!

So my question is do any of the pond vacuums really work? I'm not interested
in trying to build one myself from a Shop-Vac or similar - just want an easy
way to get rid of several years worth of dead leaves, fish waste, etc.