Step 2: Building The Automatic Siphon
After doing quite a bit of research on these systems i decided to go with a flood and drain system. It seems like the easiest system to set up and maintain and once its up and running it will run itself with very little need for intervention on my part. In my long and winding travels through the various websites, PDF's , and videos out there the most reliable way to make this system work was the use of a bell siphon. This consists of a 1/2" diameter pipe (the upstand), the 1 1/4" bell (a capped PVC pipe with crenellations cut in the bottom), and a gravel guard (everything I've read says you want to maintain about a 2:1 ratio in the pipe size). The upstand is inserted into the 1/2" male adapter which passes through a hole in the bottom of the grow bed with an o-ring to prevent leaks from the grow bed. The female adapter attaches to the male adapter from the outside of the grow bed. The drainage assembly made up of the 2 90 degree elbows and 3" long PVC pipes is then inserted into the adapter.