Nevernevernevernever----never!

[Sk8r]

1 use a fish to cycle
2 chase ph (it's rarely important: kh is what to track; and to stabilize it, you need the right proportion of kh buffer, magnesium, and calcium)
3 buy stony coral without a calcium test and supplement
4 tolerate caulerpa at all, and certainly not in a tank under 150 gallons (the only things that can possibly eat it require a large tank.
5 acclimate anything beyond 30 minutes *
6 buy a chemical cure for anything without checking with experienced RC members: this includes cyano.
7 buy a fish or invert whose adult size and food requirements you don't know. Wikipedia, if nothing else.

*[if you have a delicate specimen, [a], truly new-to-the-hobby folk should not be buying delicates at all; and [b] if acclimating delicates, you should be using the pre-set quarantine with no salinity acclimation at all: read the stickies. Do understand many fish stores keep fish in low salinities so ich won't thrive. Always check the salinity of each individual bag in an order.]