Summary

Here are some end caps for a hydroponic system.
The PVC tube is 63mm on one side, and 26mm on the other side.
The idea is to drain the water completely from the tube to supply oxygen to the roots.
The original system had no such drain connector as you see in the picture, so there was always some water level in the tube.
There are two different outlet directions available, one down, one to the side.
Happy growing...