Questions - Need some input

i am looking to add some fish. Since i have had prior problems with semi-aggressive fish, i typically stick to only peaceful fish. I am definately getting a heptus tang (spelling) and would also love to add a yellow tang at the same time. the yellow tang does say semi-aggressive especially toward other tangs.

I see these two together in alot of tanks. Does anyone have experience with both or how aggressive a yellow tang really is.
I really dont want to put him in my tank ...

i am thinking about building a sump for my 150 gal tank i will be converting from fresh water to salt water, fish with coral i am just wondering where i could find plans on how to build one out of a old spare 30 gal tank i have. i do not know anything on how to do this i mean i have been looking around the net but i cant seam to find any plans on how to build it i need to know what size pump, how to build a overflow or should i just buy a overflow please HELP thanks

Does anybody know who sell parts for the octopus skimmers or when they break you have to trow them away. Mine broke the fastening part that holds the pump. Any suggestions.

I want to set up a semi-constant water change system and I was originally going to go with the normal Litermeter setup that everyone seems to use, but then I found this: http://www.genesisreefsystems.com/.

I was just curious if anyone has had a chance to see this setup in person or anything. It seems like it is a fairly new product so I don't know how many units are actually in use yet, but it seems pretty cool. I am just looking for opinions on this setup really. I don't mind buying ...