You might want the muck vac mentioned in a thread below. You might also consider a cheaper shop vac -- with low HP relative to the size of the canister. That worked for me.

I got a Hagen Laguna pond vac for $30 & like the idea the on/off switch is conveniently on the handle one hangs on to & the pressure is from the garden hose water the unit is attached to. Problem is the pond water is suctioned up the wand and through a net bag to collect the goop x the pond bottom BUT the water is then pumped back into the pond x the bag & the pond water is stirred up horribly/yucky & could also then overflow the pond! I hope hubby can some how connect a hose to the bag outlet so that water can be drained into a tub or on the lawn outside the pond & not re-circulated to stir up the pond water or overflow it!! Either a shop vac is too strong & empties the pond & no convenient on/off switch on the hose (is inconvenient back on the cannister)or this Hagen Laguna vac can over-flow the pond & stirs up the stuff in the bottom! Surely someone somewhere can invent a more convenient & economical way to clean a small pond without draining it!!

The muck vac doesn't return the water to the pond. I think you might like it. Google "muck vac" and you'll find lots of sources with a wide range of prices.

I first got a very small shop vac. I figured it wouldn't be too powerful. The tank was full in about 10 seconds. It took forever to vacuum my little 100 gallon pond. I took it back and got a cheapie that had a 4-5 times the tank size and only a little more HP than the first. This was quite adequate for the job. I only had to empty the tank 4 or 5 times. Some people have put a drainage spigot on the tank so that you can drain it without dumping.

I was worried sick about vacuuming up fish the first time I did it. But I realized that if a fish was small and dumb enough to get vacuumed, it would just get an exciting "water slide" ride into the vacuum tank. It might be emotionally traumatized, but isn't likely to suffer physical damage.

Sharon, maybe my shop vac is more powerful than yours, but I actually have killed some small fish accidentally by sucking them up. Frogs have been sucked up and lived, but not fish or tadpoles.

Interesting. I've never sucked up a fish, but the tadpoles come through fine.

Just thought I would let you know I found a large variety of pond muc vacs in all diffrent price ranges. Check it out Im sure you will find what your looking for.

Here is a link that might be useful: Pond Muc Vaccums

Vieja, I have the same pond vac from Hagen Leguna and was wondering how to rig it so that the water would not go back into the pond. While I was reading your post I thought of an idea. Going to check my Vac tomorrow if I get time. If what I have in mind works, I'll come back and post it.

maet: well hubby attached a long piece of flexible rubber to the end of the pipe where the water went out of the net sock back into the pond. Now the water could go out the sock end on to the lawn?! Nope ..... now the vac end in the pond won't suck up anything at all! Guess the vac pressure is not strong enough to force it out the end onto the lawn like it did when it forced it back into the pond water through the net sock. I e-mailed the company Hagen Laguna about this idea in the beginning & though they had never heard of it being done, they didn't see why it wouldn't work? Well, IT WON'T!!! Let me know if your idea is different & if it works?! I wonder if the company would take the darn thing back? I can't figure out how this pump would ever be of use in vac a pond when it disturbs all the dirt in the pond & soon overfills the pond?! It does have an easy to use handle & shut-off valve convenient on the handle ... if ONLY it worked well! I will investigate the muckvac though & see if it has an on/off valve conveniently located on the vac handle & how long the handle is when in the shortest position (not the 6 ft. at the longest as shown). Ad says it does force the water out onto the lawn though! If nothing comes up tht works, guess it will be to empty the pond bucket by bucket & filter it through a screen to get the smaller fish out to place in a holding barrel as I have done in the past ... what fun!

That was the same idea that I had thought off when I read your previous post. I was going to attach something to the end of the pipe however it didn't work for you so don't think I will bother. Maybe I'll have to search to see how the muck vac works.