Are there any groupers ican keep in a 30? Any recommended stock lists? He wants colorful and active I want predatory( coming from fresh)and can I really just use a filter and a heater? How much live rock/sand will I need?i know I need a hydrometer. Should I buy saltwater or mix it myself?
I do not know of any groupers that could stay in that tank for life. Most get too big for all but the biggest home aquariums.
A lot depends on what you can afford. I would use live rock and whatever sand/crushed coral you like. I would also use a skimmer and UV if you can. The skimmer is more important, I would not run another tank without one. You might also need power heads for better circulation in the tank. It could be done with just a filter and heater but there are a lot of things that will make it easier on you and better for the fish. I am also of the opinion that bigger tanks are better tanks. They are more stable and give you more time to react to problems.
I would mix the salt myself. I think the premixed jugs of water are a scam, for most applications.
You can do predator with colorful community fish, like clowns. It has to be done carefully and be prepared to lose some expensive fish, even if done carefully. The lion fish can eat something much bigger than you would ever think.
Do some searching and reading on this sight and some of the saltwater sights. You will learn and retain a lot more. It helps if you can condense a lot of different sources of information into your knowledge base then make your own decisions.
