Encrusting Coralline Algae is what gives many saltwater aquariums their color and a good covering is the goal of most marine aquarists. Coralline Algae exists in a variety of different colors (green, pink, white, purple, red). Different colored coralline come from different parts of the world.
Unlike Brown, Green Hair and Red Slime Algae, which (frequently) grow in your tank whether you like it or not, Coralline Algae must be physically brought into your tank in order for it to reproduce and populate the various surfaces. Coralline Algae can be introduced to your tank by installing:
- Coralline covered Live Rock
- Coralline scrapings from another tank
- Commercial Coralline Algae starter packages
The more types of Coralline (green, pink, white, purple, red) that you add to your tank, the more you will see growing on your Live Rock, substrate and aquarium walls. Once you have some Coralline Algae in your tank, how do you get it to reproduce and spread throughout your tank? One simple method is to turn off all tank filters and skimmers, leaving any powerheads running. With a single-edged razor blade, scrape the existing Coralline off the front and side tank walls. The water current generated by the powerhead will spread the Coralline scrapings throughout the tank where they will continue to grow. After an hour or so, turn the skimmers and filters back on.
Coralline Algae Lighting
As with other forms of algae, Coralline Algae requires light. Exactly how much or little light is required for optimum Coralline growth has been the subject of many debates.
To simplify the outcome of most of the debates: it appears that some types of Coralline Algae prefer higher lighting, while others prefer lower lighting. Many aquarists have found that, as their tank lights get older and the spectrum and intensity fades, some of their Coralline growths actually increase and grow higher in their tanks. They also found that these growths die off in the more well lit areas and increase in the lower and/or more shaded areas of the tank when the lights were replaced, while other types increased under the more intense lighting.
So what type of lighting is best? There is no single answer. Some types of Coralline will grow better under certain lighting while other types will grow better under a different lighting. For the most part, it seems that Coralline will grow under minimal reef type lighting (our Corallines do well under 1.6 watts per gallon of a combination of 10000K and Actinic Blue). In his Coralline Algae Propagation Research Page, Leroy at GARF states that: “Lighting the live rock grow out tank with 2 Triton 40 watt bulbs to each Blue Moon 40 watt bulb has produced the fastest growth of Coraline algae.”
Coralline Algae Water Chemistry
While lighting is important, maintaining excellent water quality may actually be the biggest factor in growing a good crop of Coralline. Like hard corals, Coralline Algae is calcareous by nature, requiring many of the same things corals do in order to flourish:
- SG apx 1.024
- Calcium – 350 to 480 ppm
- Carbonate Alkalinity – Between 2.5 and 4.0 meq/L (7-12 dKH)
- Low Phosphates (Close to Zero)
- Low Nitrates (5 ppm or lower)
Many aquarists have found that performing regular water changes will keep the phosphate and nitrate levels in check as well as keeping the calcium, alkalinity and strontium at or near their optimum levels. Others have found that using Mangroves in their systems has been a simple and inexpensive method for reducing nitrates and phosphates and that using calcium and strontium additives produces the same or better results without the constant expense of sea salts and RO/DI water required for water changes.
Many aquarists have also found that using a good protein skimmer goes a long ways towards controlling nitrates and phosphates. Leroy, from GARF, makes the point for the use of additives: “We have found that by using SeaChems Reef Builder and Reef Advantage (Compare Prices) in alternating doses in our make-up water we have had no trouble keeping both the calcium and alkalinity at the proper levels for rapid coralline growth. This simple method of treating our make-up water also keeps the strontium level in our grow out tanks high enough for the coralline algae to thrive.”