The bell siphon has 2 jobs:
1. Start draining the water
2. Stop draining the water
As simple as these tasks sound, it is a balancing act getting the components tuned. These components are:
1. Water flow
2. Width and height of stand pipe
3. Width and height of bell siphon
4. Cap on bell siphon
5. Down pipe
My siphon has trouble with both of the tasks its meant to do so I might as well start with problem #1. The siphon not starting is represented by your growbed filled with water to the top of the stand pipe. There is water dribbling out of the down pipe, however it seems to be leaving the growbed at the same rate it is entering and therefore the water level is not changing and something is preventing the siphon from initiating. If the siphon isn't starting, it can be due to the water flow being too weak. Other factors that can initiate the siphon is pressure from the down pipe. Elbows and restrictors increase the back pressure which helps the siphon action to start. There may also be an obstruction to the water entering the bell siphon.
I tried adding 2 elbows to my down pipe but it didn't work. I then glued 2 rubber O-rings into the pipe and threaded in a 10mm tube which will hopefully create enough back pressure to get the siphon to start.
If adjusting the water flow and down pipe doesn't seem to be working, you may have to revisit your stand pipe and bell siphon. Because my system was previously working, and I've put plants in my growbed already, I'm hesitant to touch these elements.
Today I got my siphon going again, however the process didn't stop which is represented through the water level remaining at the height of the slits in the bell siphon. The water again is leaving the growbed at the same rate it is entering and therefore the eater level isn't rising because the siphon isn't turning off. This is due to the same factors as above except opposite.
Reducing the water flow will lower the amount of water entering the grow bed so the siphon can fully disengage and the flooding can start again. Reducing back pressure in the downpipe by getting rid of elbows can also work.
Read more: http://www.japan-aquaponics.com/bell-siphon-guide.html
I am yet to perfect the system that will work day in - day out, however there is good news! The (almost) dead thyme plant has grown new sprouts which shows that the aquaponics system is doing its job. I also bought 4 new fish but I think that the first fish is getting bullied now.
