Patti, I have been interested in building a pond vacuum using a pool pump.
There is one in the link below that looks like it would do the job.
I would like to hear if anyone else has built one and just how well it works?
"Horton"

Here is a link that might be useful: DIY pond vacuum

Horton, that looks pretty complicated and costly for me. But I appreciate the response. I wonder if I could just use a wet/dry vac with hose adapter? Although thinking about it, likely the hose adaptor opening, would not be large enough.

There was a time when every half way decent garden supply shop sold a venturi pump which looked a bit like the one pictured here; venturi pump. The difference being that both major input end and the major output end of the venturi pump had hose threads. The side input would be fitted with a tube smaller than the hose to suck liquids into the device and deliver or disperse the stuff sucked up by the small tube into the flow of the hose.

I'm think that if one could buy or build (or find on the garage shelf) a venturi pump one could suck alga from one's pond and use it to water the lawn or garden.

The spouse says the venturi pump she is using to clean her pond came with a waterbed she once purchased years ago.

I've been working through building my own vac for a couple months, now (bought a house which came with a pond, so am working on upgrading, fixing, and cleaning). Some things have worked ok, some not so well, but maybe this'll help.

For a pump, I'm using one of Harbor Freight's clear water pumps (1479-3VGA. 1" I/O), cause it wasn't expensive and it allowed me to do some experimenting without destroying a more expensive pump. Since this is a clear-water pump, it can't handle large solids (silt and mulm pass through without incident), so you'll need to build a filter for the front of it.

My first filter consisted of an under-sink 20 micron water filter element (3" diameter, 10 - 12" long), housed in a specially constructed 3" PVC housing (previous owner had left the PVC). For tubing, I used standard 5/8" garden hose (had it laying around) that I modified for the job. This filter setup worked extremely well - especially for a wild stab in the dark - but it clogged way too quickly. Something like this would probably work well for a filter after the pump if the idea was to return the water to the pond and not the lawn/garden.

My second filter used Waterbug Design's leaf trap as a guide. I again used 3" PVC (cause I had it), and made a filter element out of 1/4" hardware cloth formed into a cylinder. Since I had a lot of trouble fully sealing the first filter (against water/air leaks), I planned on hooking the filter to the pump with a length of tubing so that the filter could reside in the pond under the water. I also upgraded from the 5/8" hose to 1" tubing on the input side of the pump (still using the 5/8" hose on the pump output). This worked a *lot* better than the first filter, but it can still get clogged extremely easily in my pond - though I am trying to clean out 3 years worth of silt and mulm and leaves and rocks and pebbles and overgrown lilies as time allows (so my environment is probably worse than yours at the moment).

One major pain about this "vac" is that the pump is not self-priming, so it was originally a huge ordeal to get the pump primed and keep the system as free of air as possible. So far, the best $10 I've spent was on a 1" check valve that I put on the output side of the pump - this helped out immensely in not having to totally re-prime each time the filter needed to be emptied.

I'm in the "considering it" phase of making another attempt at the filter (I'm either going to make another filter, or cave and buy a decent vacuum). This time I'd go with 4" PVC and a larger screen element so that it wouldn't [hopefully] clog as quickly as it does, but my clogging problem is mainly caused by the pebbles getting stuck in the tubing or at the connection points rather than actual leaf/muck debris. My current vacuum configuration: 5' length of 1" PVC, connected to a 10' length of agricultural suction hose (basically a 1" clear hose with brass fittings on the ends), which connects to the filter, then a 6' length of 1" braided vinyl hose from the filter to the pump inlet. On the output side of the pump we've got the 1" check valve, with a reducer and brass hose fitting, connected to a length of old 5/8" garden hose. Even through all this the pump generates significant vacuum/pressure potential - sucking up anything in it's way and generating a pressure at the hose output similar to house pressure.

I did initially try a shop vac, but that filled up so fast that it wasn't worth the trouble to me. I also don't want to use a "mop" type of vac cause of all the sediment that would get stirred up - I wouldn't be able to see anything for a week! I've given serious thought to putting the fish and plants in a temporary holder and giving the pond a thorough cleaning, but it's just me doing this and I don't think I could get everything done in a weekend (there are some *big* rocks in that pond).

Check out Floyd's pond vac:
http://members.shaw.ca/floydn/

fred

I'm using an 8 gallon Shop Vac. It slowly gets the job done, but it's time consuming and heavy to empty. However, it does get the job done. I paid $48.00 for it.