Live sand or No

Making some progress on my tank. It will be a 37 gallon FOWLR. It has been
suggested by the local pet store that I use live sand. Instead of normal
fishtank sand. I have. If I put in a 5 or 6 pound cured live rock with
some other rocks that can be colonized and just regular sand would that not
be enough?

If you think I should use the live sand could I at leaset mix it 50/50 with
the other (read cheaper) sand?

Other important fact. For the time being I will be using the rock/Sand as
biological filter with The Penguin mechanical filter that I used iwth this
tank when it was freshwater. I have some time on this. I am going to buy
some wood today and try to build my stand. My wife doubts my wood working
skill!! =)

Thanks in advance
James