Pond Vacuums for the pond owner and professionals. The two smaller systems are not continuous. You would vacuum the muck, sludge at the bottom of the pond, slowly not to stir too much stuff up. Once the vacuum fills, it will shut off and will drain. Once it finishes draining it will turn back on again.
The MPVC continuous, has two pumps. One to vacuum and the second inside the container that pumps the vacuumed water out. So no waiting for it to for it to drain. You should always be vacuuming water and shouldn’t run it dry. Unless you unplug the secondary pump. Then it could be used like a shop vac. Again once the water fills, the vacuum will shut off until you plug in the secondary pump to drain.
All three have a net bag to collect the leaf debris, stone and twigs, so be sure to empty when it fills.
Vacuuming the pond does help to keep the muck and sludge removed from the pond. It does take time, so please leave yourself time to do the work.