Instructables

Step 3: Activated Charcoal Layer

Picture of Activated Charcoal Layer
The next layer to put in is activated charcoal or activated carbon - same thing.  This is the stuff from your Brita water filter or fish tank filter - if you've got that, toss it in there.  Otherwise, you can buy small amounts online, or skip this step entirely.  I just happened to have a whole lot of activated charcoal lying around for a future project so we took a 1/4 cup or so and added it in.  

My sister and I devised a simple cardboard chute to deliver materials precisely where we wanted them in the terrarium.  The chute, plus a push stick or brush works much better than the dump method.

The activated charcoal layer just keeps things "fresh", or so I've read.  
jodi87271 year ago
I have a few used PUR water filters, is that the same? I also just replaced the filter in my fish tank, but it is a small one may need a few more before I could use this idea. I've always wanted to do one of these. Thanks.
noahw (author)  jodi87271 year ago
PUR filters should work - even used ones.