Since a lot of people are complaining with bell siphons, I did not bother with building one for my grow bed inside a 6×8 feet greenhouse. I chose to build a simple spiral siphon, easy to start and easy to break. Here is the video (if you live inside China and can understand Chinese, click here to see video served from QQ):
Normally, with the so-called u-siphon (this is the video where I got inspired from) made out of a few elbows and two 45 degree PVC connectors, it is easy to start but hard to break the siphon. But after playing with it, I came up with this simple design.
Instead of installing it inside a grow barrel, I installed it outside to make everything external. This change is make everything super easy.