Thanks to all of the help from this forum, we rebuilt our pond last year. Everything appears to working fine except the dump valve/flush valve. We have 2 55 gallon barrels as filters and my husband put a small spigot in the bottom of each barrel to drain the muck from the bottom of the filter. Needless to say, this is not working. I drained the barrels today because they were so full of gunk that it was flowing into the pond through the waterfall. Can someone please explain to me how to install a dump valve or something to drain the bottom of my barrels. The barrels are above ground and I would like to do it in place because they are plumber and glued. I've read several DIY on 55 gallon barrels and can't find exactly what I'm looking for. Thanks.