Water is pushed from a garden hose or pump through a nozzle in the bottom of the vacuum which points up away from the pond's bottom. As the water under pressure shoots up it pushes pond water along with it which creates a current from the bottom up through the top. This effect is called the Venturi Principle.
The top of the vacuum has a fabric collection bag to trap large debris but allows water to flow through. If water isn't allowed to flow through the bag it has no where else to go except out the bottom of the vacuum. This is why venturi vacuums can't remove fine silt. A bag tight enough to trap fine silt, 20 microns or less, will not allow enough water through fast enough to create a vacuum.
Designed by Waterby Design, sponsor of this site. DIY only. no longer sold.
Muck Mop is the only venturi vacuum we know of designed specifically for use in ponds. By using a pump for power instead of a garden hose it is about 10 times more powerful than garden hose vacuums. It uses no additional water or adds any chlorine to the pond so there's no hurry in vacuuming. You can even leave it running while you have lunch and it will continue to draw debris into its collection bag. Nozzles can be cleaned. Leaf and Fine bags use an elastic drawstring rather than a cord like on other bags. When pulled tight the elastic holds tighter than cord and keeps the bag from popping off when full.
Works at 18" and deeper, limited only by reach of pole and hose. For use in larger ponds, 1,000 to 3,000 gal and larger.
Requires a 1000 GPH or better pump. 1/6 to 1/2 HP sump pump from hardware stores works great, $60 - $90. Pond pump can be used if it has a fitting on its outflow that a 1-1/4" PVC fitting can hook onto. Sump pump is easier because it can be moved around the pond so a shorter hose can be used. Also needs a $20 swimming pool extension pole.
Leaf Eater, Leaf Master
$25 to $50, try swimming pool supplies for the cheapest price. Designed for swimming pools and many of these by many different names have been sold to pool owners over the years. It's 15" diameter means it's best on rather flat bottoms with wide open areas. Uses garden hose for pressure power so performance can vary greatly from area to area and even time of day. Water with chlorine would need to be treated. We used a Leaf Eater for years in a swimming pool and it worked very well as we have very good water pressure. We've had problems with the bag popping off when full of leaves.
We had a problem with bugs crawling into the hose connection during storage with then plugged the small nozzles which can't be cleaned so the unit became unusable. A plug for the hose connection might help or storing in a sealed plastic bag.
Works 18" and deeper, limited only by reach of pole and hose. For use in larger ponds, 1,000 to 3,000 gal and larger.
Requires a $20 swimming pool extension pole and garden hose.
Spa Vac, Aqua EZ, Mini Vac, Black Magic, Jed-Vac, Uni-Vac II
$15 to $30, try swimming pool supplies for the cheapest price. Designed for spas. Same as the Leaf Eater above except with a smaller footprint so it would be easier to get in and around plants.
Works at 12" and deeper, limited only by reach of pole and hose. For use in any pond 500 gal and larger.
Most require a $20 swimming pool extension pole and all need a garden hose.
Muck-Vac, $65 to $100, is the only venturi vacuum we know of which doesn't use a collection bag and instead pushes water up and out of the pond which would be effective in removing silt. We have not used a Muck-Vac am unsure of performance in a pond and the amount of water used. Advertisements and demonstrations at trade shows show it working in shallow water but we can't find any specs on what pond depth it works. We assume it would also be easily clogged by leaves and dead string algae. But like we said, we've never used one. If you've had experience using the Muck-Vac in your pond we'd like to hear your review.
Unknown limit on pond depth. Pole is 6' so that's its basic reach. Seems to be for smaller ponds.
Comes with a 6' pole, only needs a garden hose.