Try this - copy & paste the below code into your signature, then add a [ at the begining of the code, and a ] at the end.
URL="http://www.reefsanctuary.com/forums/reef-chronicles/61896-1st-reef-tank-40-gallon-breeder.html"]Fishhound's 40 gallon breeder[/URL
This should make a link called Fishhound's 40 gallon breeder.