HI everyone! Newbie here. Need a quick answer if you don't mind...I am becoming overwhelmed (and running out of money). I am/was in the process of setting up my 33 gallon tank for saltwater but after much reading I doubt it will succeed. I have 28 lbs of live rock and live sand. No fish yet. Can I just take the water out and refill and go back to freshwater? Can I keep the rock and sand since it cost me $300?