Aquatic Facilities,Isolation and Containment

No matter how clean and hermetic your facility is, algae will find their way in.

Let’s face facts; if you are managing any type of aquatic system, you are almost guaranteed to cross paths with some form of algae. Algae spores are everywhere in the environment: in the soil, in tap water, even floating in the air. Unless you understand the conditions that promote their growth and how to prevent them, algae can quickly take over.

First, let’s understand the correct terminology. Algae is the plural form of the word, alga is the singular. So, it is incorrect to say “Algae is growing in the tank” but rather “Algae are growing in the tank.” The reason we speak of algae in the plural form is because it is always found in the plural form. Most algae are single-celled, almost microscopic organisms that exist in large colonies, although there are filamentous and a few large erect forms – kelp, for example, are algae. Known as phytoplanktons (from the Greek phyton = “plant,” and planktos = “drifters”), the single-celled variety are too small to be seen by the naked eye, but appear green when in large numbers due to the presence of chlorophyll.

There are thought to bemore than 30,000 species of algae. They can be divided into four major groups: Cyanobacteria, the blue-green algae; the Chlorophyta, the green algae; the Phaeophyta, the brown algae; and the Rhodophypta, the red algae.¹ They cross three classifications: plant, bacteria, and protozoa, but for all intents and purposes, they are considered plants. They come in benthic (attached) and planktonic (free floating) forms. Marine botany, more specifically phycology, is essentially the study of algae, as there are only a few true plants that are completely marine. Algae differ from terrestrial plants in that they lack certain structures such as roots, stems, and leaves with vascular tissue, but liken to them in that they are photosynthetic, requiring nutrients and light to grow.² Like all plants, they photosynthesize in light and respire in darkness so, while they provide oxygen to your system during the day, they consume it at night.

The type of algae that appears is an indicator of the water quality – “good” algae, many of the green varieties, are a sign of a healthy system whereas “bad” algae, the reds, browns, and blue-greens, indicate a system out of balance. The green algae can often be seen in home aquariums, because they are more aesthetically pleasing and do not tend to overrun a tank like some other species. They can also be cultivated as a filtration system. An algal filter or “algae scrubber” consists of a bed of green algae purposefully grown to reduce nutrients from, and add oxygen to, a closed water system, and in effect, “scrub” the water clean.³ In fact, the algal populations of our oceans are actually responsible for most of the oxygen in our atmosphere. Green algae are also important food sources to many aquatic species. Some grazers have a complex relationship with algae. Nudibrachs, for instance, transfer the chloroplasts from the algae they feed upon to their own tissue. There, the chloroplasts continue to manufacture food, but now for the animals instead of the algae. Because of cleaning SOPs, green algae are usually not found in facility systems as they take a long time to become established. It is the blue-green, red, and brown algae that more often first appear. These algae can quickly take over a system, much like weeds in a garden. But, while large amounts can cause problems with oxygen levels and pH fluctuations, mainly they are only an annoyance, reducing clarity and looking unsightly.

So, what causes algae to invade? Algal growth occurs when there is an abundance of nutrients, light, and CO₂ in the system. Temperature also influences their proliferation with many species flourishing in warmer waters. Nitrogenous waste (ammonia, nitrite, and especially nitrate) and phosphates are the primary nutrients utilized by algae, especially the “bad” varieties. The nutrients come from many sources: bodily waste, respiration, left-over feed, and other decomposing matter. Phosphates are added to most commercial aquatics foods and are also found in tap water. Ideally, phosphate levels in the system water should be kept below 0.5 ppm. Ammonia and nitrites may be present in new systems or during population fluctuations, when the biological filter is not yet able to complete the nitrogen cycle. The nitrate load, the normal by-product of the nitrogen cycle, is only kept in moderation by replacing a portion of the system water with new water regularly. If this is not done, almost assuredly, algae will appear.

While excess nutrients in the tank encourage algae growth, algae bloom when a light source is added. This is why you first see algae in the tanks nearest the lights. Algae thrive more on red and blue spectrum lighting, although they can adapt to the yellow/green wavelengths, as well. Aging lights produce more of the red-spectrum. Often algal blooms coincide with older lights.⁴

As for a surplus of CO₂ …photosynthesis is the metabolic process in which carbon dioxide and water is converted by a light energy into oxygen and carbohydrates. Algae photosynthesize. Need I say more?