The following series of videos are what I’ve posted on youtube to document my progress. They document everything from my first failed attempts at getting siphoning working properly to getting my first actual growth of plants.
The bell siphon is one of the more interesting parts of an aquaponics setup. I love it’s simplicity, and the fact that there are no moving parts. There are however a couple of gotchas which I’m afraid everyone trip over when trying to first build their system.
A bell siphon has essentially two phases in it’s operation:
- Initiation – This is when the water overflows the standpipe and causes a temporary water “plug” in the pipe which pulls down air and more water behind it.
- Termination – Once your growbed is drained, you want your siphon to “suck air” with a nice gurgling noise. This signals that the siphon has been broken ’cause it ran out of water. The problem you will face here is “siphon lock”.
The typical problem you will face with “Initiation” is that your rate of water flowing into the growbed is too slow. If you’re maxed out ’cause you have a weak pump, try adding a few “kinks” into the downtube that comes out the bottom of your standpipe. Do this by introducing either a PVC “reducer socket” to narrow the pipe, or by adding one or more 90degree elbows. This will help the water back up in the standpipe and initiate the siphon.
The typical problem with “Termination” is that your siphon won’t disengage, and the growbed will *not* fill with water anymore. Water will pour into the growbed and straight out the standpipe. No nutrients for your plants. Very dangerous.
I have found no clear solution to this problem. I have added a snorkel to my bell siphon, and played with the rate of water flow, and I *still* get the occasional siphon lock. Right now I’m thinking that my 6mm surgical tubing (snorkel) might be too small to affect a proper snorkel. I’ll update this post one I have a definitive solution.
Here’s my very first bell siphon test.
Here’s my CHOP2 system “fixed” with the new and improved plumbing.
I decided to experiment with two different sizes of hydroton. 8 to 16mm diameter size, and 4 to 8mm diameter size. I immediately ran into trouble with the smaller diameter clay which made it through my gravel guard and ended up clogging up my standpipe. Lesson learnt: “build a proper gravel guard around your standpipe”. Fixing a standpipe problem means completely dumping out your grow media and starting over !
Cycling your system
All aquaponics systems have to be “cycled”. Cycling is the process whereby you establish the bacterial colony for your growbeds. In an aquaponics system you don’t need a biofilter to remove the toxic ammonia produced by the fish. A bacterial colony will automatically establish itself in your growbed. These bacteria are specific to the nitrogen cycle, and will break down the ammonia into nitrites, and the nitrites into nitrates. It’s confusing. Just remember, nitrates are the good stuff. Everything else needs to be kept in check. There are test kits available for Nitrates, Nitrites, Ammonia/Ammonium and PH.
In my case I foolishly decided to cycle my system by using live fish (goldfish) to produce my required ammonia/ammonium. This is not a good idea. So many of the goldfish kept dying because there was just not enough bacteria yet to remove the toxins.
I would recommend that anyone doing this to:
- Find a commercial source of liquid ammonium
- Buy a Nitrate/Nitrite/Ammonium test kit. Once you see strong indications of Nitrates, your system is cycled and ready to accept fish.
The happiest day is when you see your first strong levels of nitrates. This means you are finally doing “aquaponics”. You now have a properly cycling system which can properly hold the fish and plants in a symbiotic relationship. But this is not the end. You’re just getting started. There is still much to learn to keep things on track
My earlier decision to experiment with different sized hydroton has yielded some interesting results :
One week after planting my first seeds I’m already seeing some very nice growth. How exciting!