After working with complex aquaponics systems, I decided to design and build an eco system that does not require pumps, filters, lights, and all the electronics and power needed to automate and drive them. The one below is fresh water. I’ve also made some with saltwater. I don’t add food, and I don’t change the water, though I do top it off. These little drops of water are kind of like earth, they have everything needed to sustain life. Just add sunlight.