This is the barebone box without the ends. Because it's dadoes, just wanted to do a dry fit before glueing the parts together
This is the outflow. Water will return to the tanks through this small opening.
This is some arrangements in progress. I seived all the lava rock I have to get some smaller ones. I am a little short in rocks. I will throw some larger ones int. I painted and varnished the outside of the wooden box. The inside is line with a PVC pond liner. Then I place a layer of geotextile then the rocks.