Aquaponics

Because of COVID and the home office, I developed an idea to put an aquaponic system on my bookshelf and grow some lettuce. After clearing three lines of books, I had space for a 40 L fishtank on rails and biofilter on top, a growbed in the middle and on the bottom (sump) tank space for cycling water from the biofilter to the fishtank.

Implemetation

I used two matching pumps with minor overflow since I had space issues (in the bookshelf). Cycle works like this:

1. Water is pumped from the grow-bed tank to the fish tank.
2. Fishtank overflow fills the biofilter tank.
3. The biofilter tank is periodically flushed into the sump tank.
4. From the sumptank, water is pumped to the growbed.

My syphon design worked fine when flushing the biofilter. Here is a cutout from the thing:

Floating plastic foam growbead also holds up to the task. Also, no issues with growlights. But pumps (water and bubbler) tend to fail.
However, the massive issue was that the fish (guppies) did not produce enough waste to make the lettuce grow. I tested it with water quality testers. The population exploded after being force-fed for a while, but the growth potential was still modest.
So I removed everything from the bookshelf except the fish tank and biofilter. Had psychological issues to dump the rats with fins overboard.