Coralline Algae is vital to a successful saltwater tank as it inhibits the growth of nuisance algae as well as making your live rock beautiful by covering it in shades of pink, purple and green. Coralline algae has the same requirements as many corals with the exception of it doing better under higher concentrations of actinic lighting.
There are a few things that you can do in order to promote coralline algae growth.
1. Coralline Algae
This is perhaps the easiest to overlook. You simply cannot growth coralline algae without having it in your tank in the first place. One of the best ways is to find a tank with established coralline algae growth and scrape it of the back wall with a razor while collecting it with a turkey baster or a siphon. Keep it submerged as it is very sensitive when exposed to air and will likely turn white and die if left out of water for more than a few minutes.
There also may be some on your live rock if you have some. It is more difficult to scrape off the rock (and you may not want to. Regardless of where you get the coralline algae once you add it to the tank turn off your protein skimmer and mechanical filtration and allow it to be stirred up and settle on your live rock for about an hour.
As coralline algae is a calcareous algae calcium is necessary in order for it to grow successfully. Think if it just like a stony coral, it needs calcium in order to grow. Your calcium levels should be 420ppm-450ppm+
Strontium is absolutely essential to coralline algae growth. I have used Kalkwasser, B-ionic and Kent Marine liquid calcium. In all cases without adding strontium I had little to no coralline algae growth.
4. Carbonate Hardness
I have had the best luck between 10-12 dkh.
Not only will growing coralline algae make your tank look great, but it also makes it much more difficult for nuisance algae to take hold. Also, if you are able to successfully promote the growth of coralline algae you are likely meeting the needs of your stony corals as well.