“I am a preschool teacher. My class is very interested in starting a worm farm. We tried it in the past, but we didn’t have any guidelines and we didn’t have success. This time, we really want it to work. Can you provide some basic information? Can we use a glass aquarium if we cover the sides with black paper? Can we hunt for our own worms to add to our farm?” ~ Linda Warning
Building a small worm farm as an educational tool for your students is an excellent idea. Not only will it help foster an increased understanding of and respect for natural ecosystems, but it will also help the children learn about environmental responsibility. I definitely have to commend you on giving it another shot!
In general I would not recommend using something like an aquarium for a worm bin because of the challenges of maintaining oxygen levels in the composting mass. Being made of glass, you can’t exactly drill air and drainage holes in it, and there tends to be a low surface area to volume ratio in this type of container, thus compounding the problem even further.
That being said, all hope is definitely not lost! I have successfully created an aquarium worm bin myself, and I know how fascinating it is when you can actually see into the system and watch what’s going on inside – definitely a nice treat for the children.
What I would actually suggest you do however, is purchase a clear plastic tub, rather than an aquarium. This way you can get a container with a larger surface area and a snug fitting lid. There is also the added advantage of being able to add holes for aeration/drainage if you so choose.
Here is a great video demonstration of someone building a clear worm bin (you may also want to read the commentary below it, since there were some additional warnings/suggestions I felt it was important to mention).
If you don’t want to drill any holes in the container, I would suggest you fill the bottom with pebbles (1 or 2 inch layer) then coarse sand (another couple inches) this creates a ‘false bottom’ where excess water can accumulate until the end of your study.
I would also suggest you purchase a small aquarium air pump and run several lines of tubing down into the lower regions once it is up and running (not all the way down though – just within the composting mass) to help keep things oxygenated. This method definitely helped keep my worms alive when I had my aquarium worm bin.
As far as keeping light out, black paper is a great idea. You should also keep the bin out of direct sunlight of course. If you REALLY want to create a fun learning environment, try setting up a small ‘dark room’ (maybe your school already has one?). In a closet or small room simply install some red light bulbs (you can find these at most hardware stores I’m sure) – the worms are not bothered by this wavelength of light, so you’ll be able to remove the paper from the sides and watch what’s happening inside.
I would recommend preparing the bin well in advance of adding worms. Fill it with shredded (and moistened) cardboard or newspaper (and shredded fall leaves if you happen to have any) then add a decent quantity of water-rich food waste (apple cores, banana peels, watermelon rinds, lettuce etc) – definitely NO meat, dairy or greasy wastes. Let the bin sit for a week or two before adding the worms. This will still be a valuable learning experience for the children since they can watch as various microbes start to colonize the bin.
For best results, the worms themselves should be purchased from a reputable dealer, not collected. Aside from the fact that virtually ALL worms you will find outside are not well-suited for worm composting, even composting worms freshly removed from a manure pile won’t be used to eating kitchen scraps, and may try to escape.