compost tea from outdoor utility sink worm bins
I wanted to share my worm composting system with anyone else who might be interested in a simple, inexpensive setup that allows for regular production of compost tea. This system has worked really well for me for 8 years now (in the warmish to blazing hot climate of Central Texas).
Original posts can be found under the gnat topic, but we were getting a little off track, so here it is again.
I use utility sinks set in the shade under the porch eaves. (In my head, they have a nice wooden screen around them, but unfortunately, reality does not yet match the dream. :)) The sinks are free standing laundry sinks, the least expensive I could find at the home improvement center ($14 eight years ago). I put sand on the bottom to create filtration, and homemade hinged screen covers on top to block critter access. 5 gallon buckets go underneath to collect the compost tea. Not gorgeous, but neat and contained, incredibly time efficient, and never a nuisance.
If you think you'd like to give this a try, start with a good foundation--these get really heavy, and once up and running, are nearly impossible to move without breaking them down. I have concrete pavers set in an inch or so of sand. If you live in a climate that has fire ants, you can place each leg of the sink in a dish/can that will allow you to keep a little soapy water in it (in season) to prevent fire ants from moving in. I didn't do this, and have had intermittent trouble with ants, but nothing that has ever shut me down. Just seems like a wise precaution.
The drain hole of the sink is covered with a piece of window screen, with a couple of handfuls of gravel mounded on top of it. Then 3" to 4" of kids' sand box sand is added, and worms and bedding go on top of that.
The sand filter is multi-purpose: it helps hold all the worms and bedding in place, provides stability to moisture levels, serves as a home for beneficial microbes (which devour potential pathogens), and keeps the tea nice and clean so no particles clog fine watering devices. I've heard that swimming pool filter sand can have diatomaceous earth added to it, so I steered away from that. Seems like it might be abrasive to any worms that come into contact with it.
For the bedding, I use shredded hardwood mulch available in bags at the local garden center. Dampened and mixed with compost and worms, it's a cheap and easy way to avoid shredding paper, and makes a beautiful compost. I know a lot of worm resources recommend paper for bedding, but I found it to be messy and time consuming. Just think of mulch as pre-paper; we've just skipped all the chemical processing that goes into turning trees into paper. Not to mention all the chemicals in the ink...in my world, paper goes to the recycling center :)
To start, the bedding may be several inches below the top, giving you plenty of room to add scraps and more mulch to cover. I move to a different quadrant of the bin each time I add more kitchen scraps. Two bins work well for my family of 4, and we do quite a lot of cooking. As the bin matures, you can either harvest the compost directly, or step up the amount of water you run though it to prevent it from getting too full.
I haven't been able to figure out how to add pictures to this forum, but I have some of the completed bins I can share if anyone can suggest the best way to go about that. I know we vermi-composters aren't officially a photo forum, but I've seen them in here, so there must be a way. Have to say I'm really pleased to find such an interesting and creative group of folks to toss around ideas with--I've learned a lot poking around, and just spent the last few days trying to read up on all the good passive solar ideas for the greenhouse I've got under construction. You guys rock!