Hozelock Cyprivac Review:
There are a lot of cheap water hose driven vacuums out there that do nothing but disappoint. For the people who dont want to pay for a 400 dollar vacuum, there are few vacuums that you can trust that will actually work. I bought the cyprivac simply because it was the only other vacuum that wasn't driven by the weak pressure from a garden hose (and those just dump into little skimmer bags).
The Cyprivac is a manual vacuum, meaning it works like a syringe but instead of pushing down forcing water out the bottom, it's valves force the water out the top when you push the inner tube back in. So it sucks water completely out of the pond. And let me say, that it works extremely well if you are strong enough. Weaker people will find that it's very hard to hold the vacuum still when you are pulling and pushing the inner tube, and that will do nothing but stir the dirt up that you're trying to suck out. It's suction power is limited only to the size of the inlet (about .5-.75in) and your own strength. When you suck up large rocks, you'll have to disassemble it and remove the rocks that way, as they wont fit out the exit tube. That's not much of a problem, and the valves are replaceable if they fail (which shouldn't happen for a very long time). I used the vacuum to clean up an extremely large amount of muck on the bottom of my pond that built up from runoff of dirty rocks up on the waterfall and dirt left from potted plants being tipped over and devoured by the fish as well as clay. It worked amazingly well and didn't destroy the wallet either. I would recommend the use of a longer hose or some helper to remove the water via a bucket as it will fill a good 5 gallon bucket in only a few motions of the inner tube, and it's likely to smell extremely bad. So if you need a vacuum, but only very rarely, the Cyprivac is probably the best vacuum you can get and have it actually work. It's somewhat long, which is good because my pond is pretty deep and big, but that will lead to higher shipping costs if you can't find this locally.
I only had one problem with the unit and that was that the exit hose is right on the handle of the inner tube, leaving little room for your hand, this can lead to you pushing the hose off the vacuum and that can get very messy and smelly if you do it as you're pushing in, or if you're pulling a vacuum from the hose being lower than the vacuum head.
Overall, I was extremely pleased with it's performance, and would recommend it.