Benzalkonium Chloride 50% (BC5050)

Modality: dip to sanitize equipment, boots and hands.
Keywords: Benzalkonium chloride, sanitize, dip 
Usage: net dip, equipment dip, hand and boot sanitizer
Dosage: 1.5 to 3.0 ml BC50 per gallon of water = 200 to 400 ppm of BC50
How to Use: put all the intended water in container first as BC50 tends to foam a LOT if agitated.  Use clean tap water but do NOT dechlorinate or dechloraminate.  Add BC50 to the complete amount of water.  Cover container when not in use to preclude dirt and debris which will “use up” (inactivate) the BC50.  Nets and other equipment can be dipped into the diluted solution and allowed to air dry. This provides a longer contact time (kill time) for pathogens.  If necessary or desirable, nets and equipment may be rinsed with plain water or water containing sodium thiosulfate to neutralize the chlorine in the BC prior to use.  Hands may also be sanitized in the BC50 solution (and it will help disinfect cuts and abrasions).
Precautions:  Large dosages of BC, > 0.5 ppm can be harmful to fish long term.

Interactions with Other Drugs: None known but products that dechlorinate and/or lock up ammonia will use up (inactivate) the BC.

MSDS (Material Safety Data Sheet): http://www.delasco.com/pcat/pdf/benzalkon.pdf 

Source:  Florida Tropical Fish Farmers, Association.

Articles: 

Other info: Alternative Benzalkonium Chloride source from Norm Meck.

Best place to get Benzalkonium Chloride is "Smart and Final".. 
Look for "LYSOL NO Rinse Sanitizer" 
This is a 10% solution of BZ and costs about $10 per gallon.
(By the way, this stuff is also used in some South Africa locations to irrigate HIV positive women's birth canals during delivery to help prevent them from infecting their babies)