Nuisance Algae in the Reef Aquarium – Part 1

Nuisance Algae in the Reef Aquarium – Part 1
By: Scott Zachow

At one time or another every aquarist experiences problems with nuisance algae. It’s not just a problem that plagues new hobbyist; the most seasoned aquarist can experience the dreaded hair algae or cyanobacteria outbreak. As Steven Pro points out in his “Use, Misuse and Abuse of Biological Controls” article in this same edition of Reef Hobbyist Online, purchasing cleaning crews isn’t the appropriate way to deal with the problem. Many people add various species of snails and other nuisance algae eating invertebrates and they are helpful, but there is a root cause to the problem; one that is not always easily found. In this series of articles I will explain the different types of fuel that allow these unsightly algae to take over an aquarium. We will also detail step by step actions taken to identify the fuel(s) that are present in my own 75 gallon reef and which parts of my husbandry still need to be changed to overcome the problem.

When people post threads on Reefland’s Forum to voice their discouragement with unsightly nuisance algae, the typical response, even from me is “You need to find the source of the nutrients.” That’s easier said than done, right? Besides, our aquariums are nothing but artificial oceans lacking the nutrient cycles present in nature. We have to add top off water (which probably contains nutrients), we have to feed our fish regularly, and often, to maintain their health (foods contain nutrients, and when uneaten leads to real nutrient problems), those same fish are producing feces (which if uneaten is nothing but nutrients) and the list goes on. Most of this is considered to lead to Nitrate problems in the aquarium, but there are other types of nutrients that cause problems and other combinations of elements that can become problematic.

A typical view of an over run area in the aquarium. Here is mix of undesirable algae is taking over.

All aquarists are familiar with nitrate, the end product of nitrification. In the nitrogen cycle ammonia is converted to nitrite, which is then converted to nitrate. In anything but the smallest level nitrate fuels the growth of undesirable algae in the reef aquarium. The sources for nitrate are uneaten food and poor quality water that is used for the aquarium. Although these sources add nitrate to the water, an aquarium that is overstocked and unable to process the nitrate is just as bad. Since the waste produced in the aquarium has to be processed, overstocking an aquarium can put such a load on the exporting mechanisms that they cannot keep up.

Phosphate is another key contributor to undesirable algae in the aquarium. Phosphorus is a part of every living animal and is necessary, but in elevated amounts, helps to fuel undesirable algae growth and also inhibits calcification. Phosphate is added to the aquarium in several ways, but more often through food and water sources. Food is a significant source of phosphate and still contributes after it’s been eaten as it is present in fecal matter. Tap water is the other main source. One difficult aspect of solving phosphate problems is measuring it in the aquarium. Most test kits measure PO4 in orthophosphate, however it may be in both organic and inorganic forms. Since most foods add phosphate in organic forms, it doesn’t come as a surprise that PO4 is often not detectable with the readily available test kits.

Silicates are another source, although this typically leads to increased diatom growth. The primary entry point for silica into the reef aquarium is through tap water. If one decides to use silica-based sand, this could also be another source. Studies have shown that silica, although allowing diatom growth to increase could be a beneficial addition to the tank (Holmes-Farley, Randy, Ph.D. Advanced Aquarist). I personally wouldn’t recommend deliberately adding silica and since the algae that we are battling are not diatom, we will exclude Silicates as a source of our problems.

Most water companies publish their water tests annually or bi-annually. Some of them test for more elements than others, but your local results should be available perhaps as easily as the Internet. Here are the Louisville, KY water results from The Louisville Water Company for 2005 http://www.lwcky.com/water_quality/ccr2005.pdf. I wouldn’t rely on the information totally; it’s always a good idea to test the water yourself. As you can see in my case, the phosphate or silicate readings aren’t even available. For Nitrate, we have 1ppm.

Lighting has also been mentioned to cause algae blooms. It is suggested that when lights age and shift in intensity and spectrum, light at the red end of the spectrum can increase the growth of algae. As where the red spectrum may be beneficial to the growth of algae, it is still true that nutrients are elevated in the aquarium. Without the nutrients, the algae would never have the necessary fuel to grow. Algae blooms in the aquarium all come back to either a lack of husbandry, or source water with undetected nutrients being used for water changes or top-off water.

In our aquarium, we have a couple of different types of algae bloomed to undesirable levels. The first and most common algae are Derbesia sp., commonly referred to as Hair Algae. This is a very fast growing algae that can quickly take over an aquarium. It does not have the ability to harm corals directly, but can by shading corals from needed light and by taking over the same substrate that corals grow on. The smallest skeletal exposure on a coral can also be covered with hair algae and that will most likely lead to the demise of the coral since it will continually and aggressively out compete the coral for space and light. Hair Algae grows in varying lengths and green colors from bright green to dark green.

A small patch of Derbesia sp. growing in front of a T. derasa.

Bryopsis has also recently started to grow in the aquarium. This algae is easily identified by the feather shaped thalli although from a distance it would appear to be common hair algae. In our tank, the Bryopsis is a deeper green than the Derbesia and has grown a lot taller. Since the hair algae isn’t too tall it would indicate that tank inhabitants either graze on it or it’s just starting to grow. As hair algae becomes more established, it grows rather long and attaches to the substrate stronger making it harder for manual removal.

The feather like filaments are visible in this picture indicative of Bryopsis. This is starting to spread faster than the other algae in the aquarium.

Valonia sp. or Bubble Algae is another that is growing rapidly in our reef. They are commonly called this because they look like green bubbles or marbles. Ventricaria sp. look almost identical and may more accurately describe what we have in our aquarium since they are better known to grow in clusters or into colonies. It’s hard to distinguish between the two since we have grown both types; solitary bubbles and groups. This may be the most challenging to eradicate from the tank since they are not known to grow simply because of excess nutrients. Once they begin to grow, if not removed, they are difficult to get rid since when they are busted, they release hundreds of tiny “spores” that settle and generate a new “bubble”.

It’s obvious why this is commonly referred to as Bubble Algae.

The last type of algae that is growing is unidentified. It is a wafer type of brown algae that grows in a similar fashion as coralline algae. It spreads in mats on the rock structure and on plastic in the tank (both the overflow and on powerheads). In small amounts, or alone, this algae wouldn’t be unsightly or problematic but it is growing for the same reasons as the other algae; excessive nutrients.

An unidentified algae growing in the aquarium. Although it isn’t as unsightly as the others, it could quickly take over the tank.