Another exciting day in the basement! Yesterday we got the whole system put together and today it was time to wipe down all the tanks and add some water. As expected, there were a few minor leaks that we were able to stop, and no doubt we will find more as the system starts to fully operate. So far we are flood free.
The most exciting part of the day for me was testing the bell siphons (also known as autosiphons). Ever since I first started learning about aquaponics, I have been slightly intimidated and impressed by them. According to quite a few folks, they won’t work right the first time but will work forever once they are correctly set up. These are mysterious gadgets that allow the grow beds to continuously fill, while periodically draining at a much faster rate. This is called a flood and drain system, and it ensures that plant roots have access to moisture and nutrients but also are exposed to a lot of oxygen. The media the plants are growing in consists of small marble size balls of expanded clay, which leave lots of air gaps so that plant roots will never be water-logged.
A bell siphon consists of a standpipe, the height of which determines the maximum water level in the bed, and a “bell” or in this case, a pipe with a closed top and openings in the bottom which come up to the minimum water level in the bed.
Water enters the siphon through the openings in the bell, until the height of water in the tank is at the top of the standpipe. At that point, water starts to drain over the top of the standpipe, eventually filling the pipe and excluding air. At this point a siphon is formed, and just like you can steal gas from a car, you can drain most of the water out of the grow bed, until it reaches the level of the openings in the bottom of the bell. If you’ve stuck with me to this point, you may want to have a look at this video, which explains it rather well.
The siphon in the video has a separate tube which accomplishes the same thing as the slits in the bottom of my bell. The siphon is protected from grow media and plant roots by a larger perforated tube. I was very impressed that the siphon ran fine on the first try, but I’m a little nervous that it shouldn’t be so easy. I actually took a video of the end of the draining, which was amusing for me, but likely not for you, so I refrained from sharing it.
Next up: rinsing dust and debris off 100 gallons of grow media and filling the beds.