[olsaltybastard]

Welcome to RAG!! Congrats on finally starting your new setup.

Live sand is generally considered useful; the rest of the sand will usually become live over time.

Hydrometers are notoriously inaccurate and have fallen out of favor with refractometers taking their place.

Mixing the water yourself allows you (the reefer) to control everything. Under no circumstances would I ever suggest that buying water is better than making your own. It may be less expensive to purchase pre-mixed water, but you don't really know what you are getting. Some shops make their own water and others may get their water delivered to them. You can also purchase water which is packaged in pre-mixed jugs.

The very basic fundamental of reef keeping is water quality. The basic equipment of this hobby can seem a bit expensive (RO/DI filter, refractometer, TDS meter) but pays off in the long run.