Everyone online seems to feel what is called a ‘flood and drain system’ is the best for aquaponics, because it means the plant roots are not underwater all the time. The key to this is a bell siphon that means when the water gets to a certain height all the water from the grow bed is drained out. I was talking to Dad about this and he said “Oh we don’t need to make one of those, we can find one in the backyard. They are in the supply tanks for urinals”. After searching in the back corner of the yard (and realising some stuff hasn’t moved for 25 years .. I need to clean up the office) we went searching at the Hobart and Glenorchy tip shops and found one at Glenorchy Tip shop for $3. It’s not very tall but it should be great for our system.
We discovered for the siphon to work well the diameter of the outlet pipe is extremely important. Here’s a bit of a sketch.