A few days ago I noticed some problems with my setup: when the pump would turn on sometimes the airflow would go back down through the source tube and start bubbling up the reservoir rather than lifting water up the lift tube. I could fix it by releasing the air pressure in the lines and letting the water re-prime itself.
Over the weekend I didn’t have much time to work with it, but thankfully every time I peeked into my office things seemed to be moving smoothly.
Today when I sat down to do some work, I heard the pump click on and once again the bubbling sound of air coming into the reservoir. I was perplexed as to why it only seemed to fail when I was around.
I didn’t have time to debug / re-prime the system at that moment, so I just ignored it for a few minutes. Then to my great surprise, it suddenly fixed itself and started delivering water to my plants again.
My theory is that sometimes, after the pump shuts off, water runs back down the lift tube and sits stationary at a height above the t-joint. When the system first turns on, the pressure from this thin, tall water column is too much for the air pump so the air starts to backflow into the reservoir. In a few minutes, the water stuck in the lift tube flows back down below the t-joint, and which point air starts flowing up again. The system resets itself and everything works.
Since I use black hose for my lift tube I can’t quite see what’s going on, but I’m curious if anyone else has run into similar problems.