I've been running a 10 gal nano tank for about 6 months now, using sand from my local beach, and seawater. I literally live 5 mins from good clean beaches so it made sense, especially as my nano was my first real effort at keeping s/w fish. Every time i get tempted to start mixing my own water I se the prices for aquarium salt here I cringe - and in goes more seawater! I'm setting up a new 30 gal at the moment, that will be running it as well