Years ago, we went to a pet store (Petco, Petsmart) or pet section in Walmart, etc. for bags of bulk charcoal used in fish tank filters. I am sure Amazon will have this too. The charcoal pieces were very similar to what was in prefilled VIP filters. We emptied the VIP charcoal containers under a hood to avoid xylene fumes captured by charcoal then refilled with the fish tank filter charcoal. If you try this, note the level of charcoal in the boxes for quantity needed. It was actually cheaper than buying prefilled boxes from the vendor's, and no shipping costs either. Unfortunately, Sakura discontinued charcoal "milk carton" packaging, probably to avoid the fume problem during filter change - a safety factor.
This is somewhat of a stop gap measure but certainly worked for us. The more recent charcoal boxes are cardboard and sealed, if I remember correctly, but careful opening and then resealing with duct tape might work. However, first VIP charcoal filter containers were made of the same plastic as the solvent containers and not easily damaged during a change. Good luck Gayle Callis HTL/HT/MT(ASCP) _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet