Often it's the things you CAN'T see that cause the fail...
The ones that sneakily do in your corals or make your fish susceptible to problems.
This is where you need a) a decent skimmer (2x your tank system volume is a good measure) to handle nitrate b) strong water flow---limp flow doesn't oxygenate enough: your fish should work a little holding place at some points. c) do your water changes to replace the micro-traces your fish/corals may use up....
In other words, its the...

Please understand about the 5 types of damsels...
'DAMSEL' applies to a number of species of small reef fishes, which is NOT helpful to a novice trying to pick out fish that won't eat each other OR the landscape. They're very colorful, will school under some circumstances, are constantly on the move, comparatively cheap, and among the hardiest of fishes for a beginner, but the catch is---they CANNOT be kept successfully in a tank under 100 gallons, and pairs are doubly problematic: multiply...

About coralline: the purple stuff...an FYI.
Coralline is a red algae that shows as purple: it binds calcium, and covers rock in a purple coat that many hobbyists find quite pretty. And it does limit where pest algae can grow. It seems to start out as a dark red velvety coat and then starts laying down the calcium-shelled purple/pink stuff right amid it.

Do you want coralline? here's how. First, obtain some live coralline. A single tiny spot on one rock will do. You can also...

Let's discuss...salt.
You'd think that salt mixes emulating the ocean would all be real similar...and you'd wonder why some cost more than others. Prettier package? Crazy pricing?

Well, not so much that...as salt for various purposes. PURE salt is sodium chloride, NaCl...but that won't do. [Yes, somebody always asks, can I use Morton's table salt?---no. That would be a disaster.]

If you look at the label of your salt mix, you'll see a very, very long list of...

178 hours with no heat or electricity---here's how I got my tank through it.
I debated where to post this, but decided that NTTH was best.
What I used: 1 small plastic bucket, bottle of Prime, bottle of hydrogen peroxide typical strength, and a lot candles, a lot of lamp oil, two sheets, and a lot of 1-pound canisters of propane with a Mr. Heater from Ace, a hunter's propane heater.
4:30 pm Tuesday 17th Nov: ferocious windstorm takes out power for 300,000 homes in Spokane region....