Maggie71 said:
I've read people's posts about muck on the bottom of their pond, assume fish poop, dead leaves, etc. A skimmer would catch some of this correct? How do you get the rest out, a net?
Very good question.
This is exactly why I have a bottom drain and and why I would recommend them. My current pond has a bottom drain and works excellently at vacuuming up all the debri and fish poop off the bottom of my pond, My previous pond had no bottom drain and there was always a layer of sediment on the bottom of the pond, it was a pain scooping out all that muck with a net, and, as you can imagine, it makes a mess of the water while you're scooping it out.
Bottom drains really aren't that complex, you just have to understand that they are designed to be gravity fed, meaning the you allow the water pressure in the pond to gently move any sediment from the bottom of the pond to your filter system, rather then trying to scoop or pump it out, both of which tend to stir or blend up the muck and make it harder to remove from the pond water.
I disagree with Waterbug that bottom drains are "worthless" without TRPs, but I agree with him that you should do a little research on bottom drain systems before installing one.
Most bottom drain are plumbed to sieves or settlement chambers. Sieves are very effective at removing the bulk of the muck that gets sucked through bottom drains, but they are a little pricey, and not very friendly to little fish. Settlement chambers are more fish friendly and cheaper to make, but not quite as effective at removing the muck.
Tangential Pond Returns (TRPs) are return water lines strategically placed around the pond to create a water current in the pond that assists in moving debris and fish poop towards the bottom drain. They are usually something designed into larger, sophisticated koi pond designs.
A steeply sloped pond bottom and aerated bottom drains are a couple other things that assist in moving bottom debris towards the bottom drain.
I can post some pictures and video of my bottom drain system if you're interested at all.