Yes I have a dense pad and a furnace filter and then the screen not too much will get past it, but very fine particles. When I Clean out the pre filter sometimes there is a bit of setiment in the bottom, but not much. If I were to possibly seal the hole where the pump comes out of the side it might element that idk. But anyway. As my bio is a 50 gal up flow filter, I have 1 1/2" hose going to the top portion of the filter and inside, if you lift the lid you'll see 1 1/2" PVC pipe that goes straight in and elbows around the center, straight down to the bottom. Now , 1/4 way up that pipe I drilled holes to distribute to incoming water and cut V's at the bottom so it wouldn't get clogged. Made a " table" of sorts to support an egg crate lighting fixture cut to fit the diameter of the barrel at that point. The middle half of the barrel is media, with another " PVC table on top of that to hold the media in place. So. The water flows up through the media, out through a 2" pipe attachment with a hose to the filter and what ever doesn't go through at that point. I have another PVC port that is piped as overflow into the pond. The waterfall feature is an urn on top and it also as bio media in it covered with lava rock for looks. Now the bio Filter has a ball valve on the bottom to use for water changes or to back wash sediment from the bottom of the filter. In all honesty I should never have to take the filter apart. Except maybe to fix a leak , which has happened already, but I was told if you do it quickly the good bacteria should be ok.
I don't have pictures on my profile yet, haven't messed with the computer, love my iPad
But maybe if it's not too hot tomorrow, I'll take some pics