Making a carboy washer out of a pump was not my idea. If you search the web you'll find many different designs. What I'm showing here is a very simple one made from a utility pump, a bucket with lid and a quick-connect with an attached pipe.
The pump is placed in the bucket and a small notch for the cable allows the lid to be closed
If you simply let the water shoot into the carboy without the use of a pipe, the washer won't work since the water that is returning back from the carboy is interfering with the water that is pumped into the carboy. The solution is a long pipe that is attached to the outlet of the pump. I got that idea from a fellow club member. To connect the pipe to the pump, I took a piece of PVC pipe, softened one end with boiling water and pushed it over the male part of a quick-connect. The quick-connect then screws onto the outlet of the pump. I was trying to connect the pipe to the pump using a full quick connect, which would have allowed for easier removal, but the full quick-connect is wider then the pipe and was sticking into the carboy opening and blocking the return flow of the water.
When cutting the opening into the lid you have to consider 2 things. A larger opening will provide a more stable support for the carboy. But if it is too large the carboy will sit too low and the outlet of the pump can block the return flow water from the carboy. This is because it will stick into the rather narrow carboy opening.
The carboy washer in action. Put the carboy onto the water upside-down and turn on the pump. I use dishwasher detergent in hot water but you can also use non foaming cleaners like PBW.