Here's my second kick at the can in making a reactor. It will do for smaller tanks but a similar design can be used for a bigger reactor.
I built this one with these criteria in mind: small footprint, MJ 1200 and with minimal external plumbing. The use of the MJ is possible because of the very low headloss. It literally blasts water directly into the chamber and the intake is plumbed with 3/4" pvc. The media chamber is 5" in diameter and 15.5" high. The overall size is 6" diameter at the flange and 20" high. The top is removable and so is the pump for cleaning. The reactor is a free flow system IE there is no valve on the effluent. It's been up and running since the summer.
View showing the bubble counter. The black tubing supplies the CO2 and the clear tubing feeds the pump intake. Another tube at the top of the PVC elbow lets the air out on first use.
Another top view showing how the MJ1200 is mounted with a elbow and union. The green tube is the tank water feed via gravity from the display above. I used the venturi that came with the MJ to help draw water into the reactor.
Top side view showing the pump intake lead to the bottom of the reactor where a simple perforated sheet of acrylic supports a sponge that keeps the media off the bottom.
Top view showing all the tubing. The little black tube on the right of the pump is where the effluent exits the reactor.
Here's a pic of my old reactor... It's a mess compared to #2 heh!?
Cheers
Clint