Continuous Flow Through Reactor is a funny name for a worm bin. It sounds complex, but it’s probably the simplest worm bin design you can have. Basically, it’s a box with a grid at the bottom as shown in the Wormery post here on this blog. Professionally engineered Continuous Flow Through Reactors (CFTR) have a winch at the bottom of the system on both sides to pull a knife-like bar across the bottom to extract the worm castings. This removal allows for more space to put your feedstock on top of the system for a continuous flow. Food on top. Castings on the bottom. Most of the worms and other critters stay at the top of the system where the food is. We went basic and used wood with some plastic sheeting as a liner for the sides of the CFTR and 2”x4” welded wire for the bottom.

The welded wire is heavy duty and while it may seem like the openings are too big, we used cardboard when we started to lay over it to keep the contents of the worm bin inside. After a couple of weeks, the cardboard breaks down and the castings are sticky enough that they don’t drop through without some sort of agitation. We don’t have the cutting bar at the bottom so I just use a rake to scratch off the castings. It certainly doesn’t work as well as a winch powered system, but it works just fine on a small scale. The 2×4” openings help a lot here. When my bins fill up faster than I can scratch, it’s a pretty simple fix to take the top layers of the bin where all of the worms are and put them into a holding space. Then, the castings in the lower 2/3s of the system can be scooped out. It’s a little bit more work, but the castings are rich and crumbly and oh so nice.

I really like the Continuous Flow Through design for worm bins because they are extremely easy to build and easy to take care of as they allow for more air exposure eliminating the worm “tea” aspect of enclosed worm bins. The leachate or “tea” that accumulates at the bottom of an enclosed worm bin is not really that good for you or your plants. It is typically high in salts and provides habitat for unfriendly microbes. If it is diluted and aerated in a compost tea brewer, it will be safer to use, but ultimately your worm castings will produce a better, healthier tea if you just use those and toss the leachate. This is why I like the Continuous Flow Through design. The open bottom and top allow for more oxygen availability to the system for what I believe to be healthier worm castings and a happier worm herd. It’s important to size your bin so that it fits your incoming feedstock. That way, your bin isn’t too small or too large to accept the incoming food and can be dealt with accordingly to avoid odors.

So even though my CFTR isn’t quite like the engineered systems, it works extremely well and the price is within anyone’s budget. Being able to build a system to match your needs is crucial to a healthy worm herd that can take care of your feedstock. The cool thing is, once you’ve built one, you can build another fairly easily should your feedstock increase. And on top of all of the benefits, Continuous Flow Through Reactor just sounds cool.