I've been looking at the Oase Pondovac 4 because it apparently pulls water dirt, leaves, etc up then separates the muck from the water into a separate removable chamber. Is this correct? If so, does it return the cleaned water back into the pond ow whereever it's directed via a second hose for output? Also is this vac overkill for a small pond like mine?
I'm not sure exactly what you're referring to. This vac has 2 chambers inside so it can pump dirty water out while allowing you to continue vacuuming. It doesn't exactly separate the muck from the water and send the water back to the pond. At least I don't think so. A regular shop vac only has 1 chamber so when full you have to turn it off, dump, and go back to vacuuming.
I have seen a bag, I think from Oase, that you pump dirty water into and it "filters" the water so "clean" water returns to the pond. But the returned water is far from clean and the bag can clog. I haven't seen it sold in years.
IMO when vacuuming silt no water should be returned to the pond. Silt is way too fine to be filtered out in any kind of effective way. So basically you're returning some silt back to the pond. You'd be saving like 100 gal of water maybe. And virtually every pond with a lot of muck could also benefit from a water change. Water is pretty cheap.
Whether you like one vac or another is almost entirely subjective. And the type of pond and the type of debris has a huge impact.
I've seen videos of vacuuming where the user sees a little string algae in the vac, a bit of dirty water coming out and they just go ape saying it's greatest thing ever. I'm looking at how dirty the pond water still is and not impressed. Two people seeing the same thing and two very different opinions. But if they're happy, I'm happy for them. It's just a hobby.
For me the problem with any sucking vac is the nozzle getting clogged. There can be leaves in the muck, lots of string algae, sticks, small rocks in the pond. Clog, clear. Clog, clear. Another pond might not have sticks, a lot of string algae or leaves or the leaves are fragile and there will be few clogs.
So what I do is first remove the big stuff with a
leaf rake or a
venturi vac. That stirs up the muck and makes the water very muddy. But no water is removed from the pond. I vac until I'm not getting much in the bag any more. I wait a few hours for the muddy water to settle, or a day or week. Then I vac the remaining silt with something that removes water from the pond. I use a
Silt Vac for that but there are
other options, including the Pondovac.
Ponds like Aquascape is designed to require emptying and cleaning because of the loose stones and rocks. Vacuuming doesn't work very well for those type ponds.
You just kind of have to find what works for you and your budget.
One thing though, if you vac with a leaf rake or venturi every few weeks in summer the build up of silt will be greatly reduced so silt vacuuming might only be needed once every few years.
Last things...critters that consume muck. Yes, it's a whole ecosystem. And it has absolutely no meaningful effect on the amount of muck in a pond. A cow eats hay and drinks water. So if you but a few bales of hay and a bunch of water in your living room and add a cow to "clean" your living room you are going to be very disappointed when you return in a week. Your living room won't exactly be clean, but yeah, most of the hay will be gone. It would be better to say bacteria and critters convert organic material into other kinds of organic material. At the very end of the process organic material does finally break down into chemicals. But virtually all ponds produce waste so much faster than it can be broken down it isn't even worth considering imo.
