Over the years I've seen many types of vacs for ornamental ponds of which most don't work very well. Some of them get rave reviews by one person and someone else will report terrible performance. It depends on each individual pond. A pond vac will work well for one type but not another. The best inexpensive pond vac I've seen is by WaterbugDesign and you can see it at Muck Mop.
The vac shown on this page is not inexpensive. I know of several versions of this type vac being used by businesses that clean ponds commercially and a few individuals with larger ponds. I built this vac for a lovely couple that have a 10,000 gallon pond. There are versions of this type vac that also include a small pool filter and a 3-way valve so the heavy debris can be pumped to waste and then it is switched to pump through the filter and direct the water back into the pond. One way of obtaining the same results without the addition of a filter is to direct the outlet hose into a container with quilt batting or other mechanical media with the drain going back into the pond.
Our commercial site: http://www.koivillage.com
One - Hayward 3/4 HP Super Pump
Two - 1-1/2" x 30' swimming pool vac hoses
Two - Quick release couplings (These have spring loaded locking pins
One or Two - Swimming pool vac heads
One - Extension pole to fit vac heads
One - PVC double outlet box
One - PVC double outlet box cover with switch
One - 15 amp switch
One - 15 amp flush mounting outlet (You can use a GFCI outlet if you will be pluging the power cord into an outlet that isn't GFCI protected.
One - Heavy duty extension cord (No. 14 AWG) [American Wire Gauge]. It's best to use an extension cord 50' or less. I used a 25' cord.
One - Male plug with ground.
Three - 12-10 AWG Ring Connectors
One - 1/2" male wire clamp for installing the cord to the pump.
Assorted nuts and bolts.
These pumps are designed for swimming pools and come pre-wired for 230 volts and are normally hard wired with No. 14 AWG Romax electrical wire. In order to change it over to 115 volts and connect your plug wire you'll need to remove the motor cover. The black plug shown in the picture below has an arrow on it. I've outlined it in red since it isn't visible in the pictue. It will be alined with the 230 volt arrow in the white area. Disconnect the plug, rotate it and plug it in so the arrow points to the 115 volt arrow in the white area.
I cut 18" of the extension cord that has the male plug and installed it on the pump motor. In the pictures I show 12-10 AWG spade terminals. I realized it would have been easier if I had used ring terminals instead. You don't have much room to work and since the braded wire used for extension cords is larger that the solid wire used in Romax you need the terminals that are made for larger wire.
Don't remove the covering from the wires until you have run it through the clamp and hole in the motor. Put the wire through the clamp and the hole in the motor but don't screw the clamp in until you have connected the wires. Remove about 5" of the outer covering to expose the three wires and cut the black and white wires shorter as show in the picture below.
It's not show in the pictue but it is easier to connect the wires if you unplug the black internal plug while you work. Connect the green wire (ground) to the green screw at the top, the black wire (hot) to the brass screw in the middle and the white wire (netural) to the brass screw at the bottom. Once you have tightened the screws and reconnected the internal plug with the arrow pointing at the 115 volt connection you can screw in the wire clamp and tighten the clamp screws.
This is a three position dolly and I bought it at TSC (Tractor Supply Co.) for $59.00. With a little modification it works great.
I cut the toe plate extension that comes with the dolly and bolted it to the frame so I'd have something to mount the pump to.
I drilled the holes in the dolly toe plate to mount the box, ran the wire through the clamp and tigented it first so I could cut off some of the screws in the clamp since they would hit the toe plate. You can get the PVC electrical box with a 3/4 inch female threaded hole for the cable to come out of but they were out when I bought this one so I got the 3/4 inch socket and a 3/4 inch socket x 3/4 inch female and used a short piect of 3/4 inch pipe to glue it. Mount the box on the toe plate of the dolly.
Install the switch and outlet. Remember, you will need to use a flush mounting outlet or a GFCI outlet so the cover will fit. I split the outlet so I could control the bottom plug receptacle with the switch and the top plug receptacle would remain hot. That's why you see a red wire in the picture. I used it to bypass the switch to the top receptacle. If you don't know how to do this and would like to wire yours this way you should find a friend that knows how.
Before you mount the cover use some "Plumbers Goop" or other waterproofing in the hole where the wire exits the box.
Before you install the cover make sure the switchs are in the off position. Remember to use the gasket that comes with the cover.
Even though these pumps are self priming it would be advisible to include a 1-1/2 inch swing check valve in the vac hose just after the vac head. Put the vac head in the pond where you want to start an fill the hose before connecting it to the inlet of the pump. Fill the leaf trap with water and turn the pump on.