Ok folks, I am back on MFK and gettin back into the hobby!!! I've been gone for some time but I am coming back strong now having finished some college and with a two year old, new employment, life has been hectic! I currently have no set ups but will definitely be setting up my betta operations again and I have a major question. OK it's like this I have a 30 gal that I recently got and I have honestly NO IDEA what to do with it. I am an intermediate hobbyist but I read like a fiend about everything and plan accordingly. The tank has a modified thing in the back that is like a box with a pvc pipe that snakes out the back to a clearish pipe and I have no idea what it was used for. Should i go salt water? Fresh Water? I want maybe one large interesting fish, what is the largest I could go and how many? I know the rule of thumb the 1inch of fish thing, but im really stuck here folks, help me out!