would a couple of these be easier/cheaper working alternative in place of a diy carbon filter
http://www.ebay.com/itm/Activated-C...595?pt=LH_DefaultDomain_3&hash=item27fbf73c53
http://www.ebay.com/itm/Activated-C...595?pt=LH_DefaultDomain_3&hash=item27fbf73c53