Swirl Filter/ Vortex Filter
In aquaponics the waste products of the fish is used by the plants as food. In a small system there is usually not enough poop produced to cause any problems. It is broken down, and used by the plants, but in some of the larger systems with large fish a build up of fish poop can cause problems, including disease and contaminants growing in the poop.
One of the easiest ways to collect and remove excess solids from your system is through a swirl filter/ vortex filter.
My indoor system is small enough that I probably don't really need one, but I wanted to build one to see how it works, and experiment on it a little.
Mine is built so that the excess solids are removed from the bottom of the fish aquarium by a piece of PVC pipe that sucks up any of the poop or left over food. It is then emptied into the filter at a right angle creating a swirling motion, as you can see in the pictures below.
When the solids enter the filter they move to the outside of the container, because of the swirling motion of the water, and settle to the bottom of the filter. The "clean" water is then removed out of the center of the filter, at the top of the water when most of the solids have been removed.
You can see the solids that have collected at the bottom in this picture.
Most filters of this design have a cone shape at the bottom which funnels the solids to the bottom where there is a valve to release the solids out. I just have some gold fish which don't create a lot of mess, so I just use one of the gravel vacuums you can get at any pet supply store to clean out the poop every couple of weeks.
The solids you remove are a great fertilizer for your dirt garden, take it and dump it into your grow beds.