Ok.. I made my moving bed slightly different than most.. my inlet is ran about half way down the barrel and turned back upwards in the center of barrel.. I used a solids handling "T" (because I had one) at the top bend downward. It's capped with black cap. This is all 1&1/2" pvc. Here's the rest of the input plumbing The upturn is caged to keep any media from being syphoned back into pump, or clogging the input plumbing anywhere... should the power go out etc... No picture but the output plumbing is 2" PVC. It goes down to an inch or so from the barrel floor, and is wrapped with 1/2" mesh plastic hardware fencing to the floor of barrel, ziptied on. Making a 1" gap between pipe and floor with a cage to keep media from escaping into pond. The reason I built this way is to mimize the air requirement to Power the movement. (The pumped water does some of the work.) The air pump is an 18 watt, 570gph, $15.00 eBay special. It takes 1/4" line.. I ran it down to bottom of barrel.put a"T" on it with a 8-9" loop. I drilled a hole every 1/2" in the loop. It's ziptied to a scrap of light grid. I set a rock on the grid to hold it down. This also allows me to easily pull it out, should the holes clog with build up, and it allows me to adjust placement for best performance. Hope this helps someone. I should have made a thread when I built this, but, it's been running for a year or more.