I've used Koetter Fire Protection several times, and they will fill your tank, but if you show up after 11:45 be prepared to wait an hour for lunch break to end (50/50 if someone there will do it vs. tell you to wait). Lately I've been using Metroplex Welding Supply off of Northwest Highway. A bit cheaper, they'll do an exchange, and an all around friendly and helpful group of guys. They're pretty good for welding supplies as well (go figure). After I showed up a few times in a row (every 3 months or so for my freshwater tank, 20 pound) they even swapped me for an aluminum tank. Only downside is they underfill during the summer when it's really hot out.
