I was running new lines to fit the twin 55-gallon barrels I had installed as a pre-filter before my biological filter system. I glued my pump in place and let the water flow through the pipe. The barrels filled and turned my pump system. Back in business. This ran fine for 6 weeks, then they slowed down. 

I went to check the pre-filter/Settlement barrels and found them filling slowly and then emptying quickly before the barrels were fully filler. Problem in the 2” line that fed the barrels I ventured. I jumped in the pond and put a piece of equipment in the bottom drain out-flow pipe. Now this piece of equipment is made out of rubber, has a hose attachment, and a hole at the other end. The way it worked was you attach a hose, placed it in the pipe, turn on the water and the rubber piece swelled to the interior of the pipe. This caused a blockage in the pipe, the small hole filled the pipe with water, and water pressure builds up. Think of it as a more aggressive plunger. 

I went back to check my pre-filters and they had little changed in status; must be something with (in) the 2” in-flow pipes. I dug out and exposed twenty feet of buried pipe. That’s was when I uncovered my potential mistake. Twenty feet of pipe = yes; but only 19 feet of 2” pipe. The rest was two 2” to 1 ½” adapters, small pieces of 1 ½” pipe, and one 1 ½” check valve. I got out my trusty PVC pipe cutters and cut out that check valve. Yup there was the blockage. 

What hampered my pipes to deliver water to the pre-filter? A wayward koi, probably thinking it could shelter under my bottom drain top. But not with the extreme suction of my Sequence pump; a +++++ aquatic black hole. Probably fit snug on its trip through the 2” pipe, but ran out of luck when it encountered the check valve death trap. It was impaled on the valve mechanism.  

A couple of 2” connectors, a piece of 2” pipe, and the pond filtration roared back to work. Back in business; minus one wayward koi.