Flood Drain / Bell Siphon

Continuous flooding and draining of the aquaponic grow bed using Flood Drain /  Bell Siphon

After researching the internet for many months, I could not find any siphon design for this kind of large grow beds, all I could see is dutch buckets, blue drums and PVC tube based system consists of a maximum 1" drains. For draining 3000 liters of water in each grow beds, I needed a much bigger valve than the usual 3/4" or 1" drain. Decided to build a raised tank and setup various sizes of flood drain valves before I actually make it under permanent concrete.

After finishing the experiment, used this 5000 liter tank for drip irrigating 20 small fruit trees ;)

It took several iterations and different PSI water flows to calculate the size of bell I need for the grow beds. Finally chosen, 3" bell, 4" bell doom, 1.5" drain pipe and 6" gravel guard. Forgot to take videos of the experiment, my bad ;'(

Bottom L angle and drain pipe of the siphon is permanently fixed under concrete

3" to 1.5" reducer is used to make the bell pipe

4" pipe and end cap (dummy) is used to make the bell dome