Thanks Steve, I understand the division of valves, in this case though at least for us guys with fish tanks, a gate valve is usually one used for fine control and we usually don't bother with the "knife" style gate valves.
What I thought I needed was something just to divert a flow path. But I had about 8" to work with on 2" pipe so a ball valve and a T would simply not fit. A gate valve or a knife valve would, however, and the reason I was asking is that it's easy for me to pick up a "up down gate valve" and not so easy to pick up a "turny-turny-turny gate valve" (there, is that better if I call them THAT???

) and besides, I didn't WANT a turny-turny-turny gate valve when all I wanted was a "wooshy grunty single sweep push action" gate valve.
After all is said and done though, I think I'm going in a different direction with the piping after all. I'll probably buy your dead pump instead. Let me have a payday here and I'll be in touch..