I don't have a pic now but what I use is a large plastic flower pot. I put the submersible pump in the pot, weight it down with a couple of bricks, and then stuff the top with nylon pot scrubbies in laundry bags. I also put a nylon rope loop with a cork to keep the rope visible so I can easily snag it with a pole with a hook on it. I have to clean the prefilter about once a month.

mwp, check out the pre-filter basket I made from two vegetable colanders in the post linked below.
"Horton"

Here is a link that might be useful: Pre-filter basket

I must just not be very crafty, cause I tried making one out of a rectangular rubbermaid-type basket(with lots of holes in it) with a lid and put the pump in it and filled it with scrubbies, but it was a mess to deal with. I end up buying Sunterra's box filters, and they are so easy to use and clean. I try to find them on sale at the end of the season and buy a couple.

Horton that looks great. Is this helping keep the pond clean?

Being on a hillside with two streams, I have periodic siltation problems. With a little time and koi clay everything settles out. Some of the material comes with rain, some with a lot of splashing water. I keep working at covering exposed areas but will never stop it all unless I run less water.

I have a large skimmer with net, brushes and two Matala mats along with a filter pond of some efficiency. I have tried a retro bottom drain and don't think it does anything good.

I now have a couple fish and think it might be good to try to reduce the sedimentation. I am going to try activated charcoal but now wonder if a small submersible with pre-filter as Horton describes would be a little extra help. Couldn't be simpler to construct.

The off-and-on silt doesn't bother me, just the quality of water for fish.

Thanks - Mike

mwp, that type of basket screen's purpose is to prevent the pump from sucking up pea gravel or anything hard that may damage the pumps impeller.
The scrubbies will screen the water even further and become a small bacteria colony. It will probably require weekly cleaning, by washing it out with a blast from the garden hose.

I use one in a small sump, that filters water to a pond statue that spouts water into my bog type pond/garden.
I clean it about twice a season.

The main pond water is drawn from the pond, through a bottom drain and surface skimmer.
It then passes through a mechanical filter pad located in a 50 gallon barrel sump. I pump out the silt and other sludge from the bottom of this sump barrel once during the season and again in the fall in preperation for winter.
From the sump barrel the water is pumped to a home made filter system [ Rubbermaid totes], after which it returns back into the pond via a small waterfall.
The water in my ponds is crystal clear all year round.
I use bird netting, pot scrubbies, furnace filter pads [the blue cut to size ones] and last, quilt batting to "fine tune" the water before it returns to the pond.
My pond capacity is around 2000 imperial gallons and the filter system capacity is around 125 gallons in total.
"Horton"

horton,

Thanks for the follow up. I have added this to my pond as well as another bio-fitler. Hope to see results soon!

My pre-filter is basically Horton's with the addition of some cheap netting (bridal veil kind). I'm cleaning it about every 2 weeks right now. It does protect the pump great. The wind blew over a pot the other day scattering pea gravel about. Some gravel made it into the baskets but not through the netting and scrubbies. Hosing it off doesn't seem to work for me, though. I have to unpack it and hose off the parts and re-pack it. Messy job.
Vanessa

I made a frame out of 1/2 inch pvc plastic pipe and fittings to hold it together.You can cut this to make a frame that fits perfect in your skimmer.Then I bought those nylon scrubbies,
2 in a pack at the dollar store.I got 5 packs.
Cut the the string that holds them together and you end up with a piece around 3ft.long,Tie some together and then You can then wrap this around your frame.This works great for me,My pond stays pretty clear. I have to clean it off every 2 to 3 days.Total cost of everything for filter around 12 dollars.
Lefty7

i took a mesh planting pot, put the pump in it and fill it with lava rock.it simple and works greatand easy to clean.

I made a frame out pvc plastic pipe. I bought round nylon scrub pads at Dollar store in the bath section. I cut the string that hold it together and then wrapped it around the frame. This worked out very well and filters a lot out of
the water. This is cheap to make at around $10.