We have all seen worms crawling out onto the sidewalk after a soaking rain, seemly gasping for air. That they choose exposure to the sun and hungry birds to the water logged soil seems to tell us that worms don’t like soaking wet environments. And what is an aquaponics grow bed if not a soaking wet environment?
The difference with aquaponics worms is that they do not remain constantly full of water, but rather flood, and then drain. This allows for a “drying out” period between soakings that also encourages air circulation within the grow media.
The most important reason why worms thrive within aquaponic systems is oxygen. The reason why those worms crawl from the soil to their death on the sidewalk is not because of the water, but because the water has forced the oxygen out of the soil. In aquaponics, however, not only does the flood and drain action pull oxygen into the grow bed media, but the water that is circulating throughout the system is highly oxygenated. In fact, we have found worms thriving within our sump tanks!