lowest point in my filter room is likely 5 feet lower than where my 4 inch line enters the ultrasieve III. I have a knife valve where the 4" line comes up out of the floor to stop flow when I need to. I believe the manual says to have a purge out line as low as possible to flush the bottom drain. This is recommended even if my pond is a bare bottom pond? Also I guess my main question is, I could always just install a T as low as I can get it in the filter room and open it up flooding the room then suck it back out yet the rest of the time when the bottom drain is not being purged, it would be running past that T and wouldn't that cause tremendous turbulence/friction and slow down my flow?. I was considering making a removable section of pipe to take out when I want to purge the bottom drain, that way when im not purging its just a strait smooth shot to the sieve. I may use a short piece of pipe with ferncos on each end or a union on each end of the short piece of removable pipe.