Here is my Bell siphon/ growbed how to:

I start with a 30 gallon plastic barrel I get for free from the car wash. I cut off the top with the buttress thread fitting so that the barrel is 12" deep. I cut a 2" hole in the bottom for a bulkhead fitting for a 1" PVC pipe.




Next I cut a section of 1" PVC pipe long enough to reach 3.5" from the top of barrel.


I made the bell housing from 2" PVC pipe, a 2" threading cleanout cap, a cleanout cap, and 1/4" clear plastic tubing.


In my prototype I drilled a 1/4" hole in the side of the cap and glued in the tubing. It just goes in the cap so it is open to the middle of the cap. It is run down the side of the bell cover and I temporarily secured it with rubber bands. I'll work out something to hold it in place later. This is a working prototype. The bottom is notched out with a router 1.5" prom the bottom. The top of the cap is 11.5" from the bottom. The clear plastic tubing extend down to .5" above the notch.

Next I made a strainer from 4" PVC pipe 12" long:

I drilled 2" holes in it at the bottom. The bottom is covered with 4" screen pipe to keep the gravel out. The gravel holds it in place. I did not glue it to the bottom, but probably will in the production run. It shifted off center as I added the gravel, but it did not effect the operation of the unit.

I used river gravel from Home Depot for my prototype bed. It is too expensive for my production run, so I'll get the rest from the quarry. It took 3.5 cubic feed to fill the barrel.


You can see the outer strainer with the bell siphon inside. The zip strap keeps the sides from bowing out.

The siphon drains the barrel to 2" from the bottom and triggers at 11" from the bottom. It drains in a little over a minute. I tested it with a fill rate of .5 gallons per minute. That took just a little under 10 minutes to fill. I'll be playing with the fill rate to see "How Low Can You Go" and still trigger.

All in all it was a very satisfying afternoon.