I spent the afternoon in the greenhouse making some changes to our aquaponics system. When we initially setup the system, we put two beds above the others. These beds were dedicated to raising duckweed and are setup to be a constant height of water with no other media in the bed. We have had to clean the beds several times since water comes in directly from the fish tank and then settles out in the bed leaving a lot of fish waste in the bottom of the tank. We also have a fingerling tank that is fed directly from the main fish tank and has similar issues.
Today, I moved gravel from two of the lower beds into the two "duckweed" beds. Now, water is pumped into the two upper beds and filtered by the pea gravel media. One of the beds feeds the two beds below which will now be used for duckweed beds (with no media) and the other bed feeds the fingerling tank. This means all water is filtered through media before being moved into either the main fish tank, the fingerling tank or the duckweed beds. Hopefully, this will help to clean up the water some.
In the cleaning, I did find a couple of fish. One turned out to be a goldfish from the initial fish we used for cycling the system. It is now in the outdoor pond with the other goldfish/comets. The other looks to be a tilapia and has been added to the fingerling tank.
It was hard work, and I was filthy when I finished but I am hopeful the system will function better with all water being filtered. And, it was a lovely day to be playing in the greenhouse.