Well, I built the chamber and it worked pretty well at keeping the bigger
stuff out of the pump. When I was done, I had about 2 inches of settled muck
at the bottom of the chamber and very little settled out into the wading
pool that I used for my discharge.

Here's what I did:

Grabbed a 5 gal. pail with lid from Home Depot. This pail seals air/water
tight when closed. Built two bulkhead fittings by taking PVC plumbing
parts -- essentially a male adapter fitting into a female with two rubber
gaskets in the middle. I carefully cut two holes in the top of the lid using
a utility knife, one in the center (return to the pump) and one near the
outside edge (intake from vac hose). Here was my technique -- I drew a
circle using the inside of one of the adapters as a guide. I used the slip
end, not the threaded end. The slip end is slightly larger and big enough to
allow the threaded end to screw into the hole. I extended the utility knife
out to its first position and then carefully used it as a punch going all
aroung the circle one or two times. Then I connected the dots carefully and
pushed out the circle.

If I was doing it again, I might go buy the appropriate sized hole saw to
speed the process, but it didn't take that long.

The male end of the pvc adapter had a snug fit and screwed in, so the lid is
sandwiched between two of the gaskets. I also used a little silicone grease
on the threads to be able to get completely tightened down.

On the inside of the center hole (discharge to pump), I attached a few
inches of PVC, and to the end of that, I attached a metal mesh basket as a
screen to prevent larger particles from making it in and to the pump. This
is like a wire mesh sock that slips over the end of the PVC. HD sells them
in packs of 2 and they come with a little zip tie.

On the outside hole (intake from vac hose), I attached a piece of pvc and a
90 degree elbow so that the elbow was about 3 or 4 inches off the bottom. I
aimed it along the edge so it will create a swirl inside the bucket.

On the outside of the lid, I attached the appropriate vac hose accessories
to connect either to the pump or to the vac hose.

To operate, I first took the bucket and filled it completely. Then sealed on
the lid, hooked up the hoses and turned it on. Initially, the air in the
hoses will purge into the upper part of the bucket, but because both the
intake and discharge are under water, this did not affect the suction.
Fortunately I made the discharge hose long enough that it remained in the
water after the air had purged from the hose. I had thought about installing
a check valve on the intake and filling the hose with water manually as best
I could, but it turned out it was not needed.

After finishing all of this, I saw an in-line leaf trap that would have done
much the same thing, although lower capacity. However, that device was north
of $50 on line and my device was probably about $10 and it was kind of fun
to build and operate.


"Remydog" wrote in message
news:aMijc.43985$w96.3533537@attbi_s54...
I'm thinking of using my pondmaster 3500 as a vacuum to get the gunk off
the
bottom of my pond. I don't use a bottom drain for fear that if something
goes wrong with the external plumbing and I'm not around, the pond will
drain. Instead, I have the pump connected to two inlets -- first, an OASE
no
niche skimmer and second to a drain about 18 inches off the bottom. As a
result, lots of stuff has settled on the bottom, particularly the deepest
part. My leaf vac gets the larger solids, but the mulm goes right through
the bag.

I want something I can use for my once a year cleaning to get up the mulm
and leaves. I installed a T in the line from the skimmer that I can attach
to a vac hose. I can then shut off the skimmer and drain using a ball
valves. Doing this, everything will pull through the vac hose on the T.

I was told by the folks who sold me the pump that the impeller is very
strong and can handle most of the gunk and stuff on the bottom and even
chew
through the partially decomposed leaves. However, to avoid pulling too
much
directly through the pump, I as thinking of creating an air tight
settlement
chamber as follows:

Take a large airtight plastic bucket, much like bulk drywall mud or
sidwalk
melt is sold in. Add two bulkhead fittings to opposite sides of the
container. On one of these I would attach a 90 bend directly down the side
to about 6 or 8 inches off the bottom, add another 90 so it would point
along the side parallel to the bottom. Now water entering this path would
be
swirled into the tank. This would be the end to which the working end of
the
vac would be attached.

The exit line would traverse from the second bulkhead fitting to the
middle
of the container, then a 90 degree bend down a few inches and place a
strainer on the end. This way, it will be several inches off the bottom
and
centered in the container, thus out of the swirl.

This would be attached to my T inlet toward the pump. On the outlet side
of
the pump I have a similar T which I would drain into an inflatable pool to
get the dirty water out for final settlement before adding it back to the
pond. This would keep the filter from being overwhelmed.

Has anyone tried this or something similar? Other ideas welcome.

Remydog