Questions From a Newbie

[kwirky]

live rock performs denitrification to a certain extent. This lets you keep a little more fish than normal but you can't overload the system.

Also the "pounds per gallon" system depends on the type of rock. Fiji rock is medium porosity. Indo rock is VERY porous. The more porous the rock the better it will denitrify (and the less it will weigh, thus the less it will cost).

It's pretty hard to jam some tanks fuller than 1 pound per gallon of indo rock while fiji rock would be easy to jam in 1.5 pounds per gallon.

Whatever the case I recommend as much fresh live rock as you can fit for your first tank and I recommend as little sand as possible for the first few months. You can buy your rock from fellow hobbyists or from a store. Getting it from hobbyists means it'll have mostly died off and all the cool (and sometimes not-so-cool) hitchhikers will have disapeared. Fresh rock from the store is full of all sorts of life but you'll have to cure it probably.

As for substrate, there are different kinds. For sand most people use argonite which comes in "normal" grain size and sugar grain. I'd stay away from sugar grain unless it's going to be a VERY shallow sand bed (less than 1/2"). As for crushed shells you can mix it with sand 50/50 and you get a pretty nice substrate that sand-sifting inverts will enjoy (along with fish that make their homes in the sand like blennies).

Welcome to the hobby and have fun learning. Lots to learn for ever n ever