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The Reef with Two Brains

Cyanobacteria Control

Algae Control

Whenever nutrients meet with light in a reef aquarium, algae and/or cyanobacteria will always be the result.

Determining the source of the nutrients then setting a course of action to reduce or eliminate them is the most useful way of dealing with unwanted algae or cyanobacteria. If the nutrient source goes undiscovered, it is our opinion the algae or cyano problem will be a long term, frustrating and expensive-to-fix misadventure for the aquarist.

The following text is based on our experiences with cyanobacteria and is by no means the only way of treatment.

 

Cyanobacteria

Causes of Cyanobacteria Growth:

From what we've read, cyanobacteria, also known as slime algae and blue-green algae, is caused by the presence of phosphate in a lit aquatic environment.

Phosphate enters a reef through tapwater, deteriorating fish waste and plant material, leftover food, and some additives.

Inadequate or no skimming or the long term use of poorly-cleaned mechanical filtration will hinder the export of phosphate thereby fueling cyanobacteria growth.

Cyanobacteria in our Reef:

About five months after setting up our 75 gallon reef, red and green cyanobacteria began growing on the glass below and level along the front and sides of the tank.

A month later, the "wait-and-see method" the cyano control had only resulted in the stuff spreading. Eventually it covered the entire surface of our 4" deep sandbed, and was beginning to grow on the live rock.

Treating our Reef for Cyanobacteria:

Early, and unsuccessful, methods of control and eradication included:

• changing old tubes (a good idea, anyway)
• feeding 20% less at each twice-daily mealtime
• positioning the two powerheads lower in the reef and at slightly different angles than previously positioned
• removing one large chunk of live rock to better facilitate better water flow
• picking the cyano off the sandbed in various places, though within days the cyano regrew

Other methods that we considered but rejected:

• sandbed vacuuming, which would have removed sand and micro-fauna
• using short term carbon filtration to remove dissolved organic material the skimmer was somehow missing. This method was rejected because the carbon we had on hand tested positive for phosphate leaching.

Even though we tried several courses of action to eradicate the cyano in our reef, it unfortunately remained. However, we still sought a solution and it came to us in a suggestion from someone posting to a reef newsgroup. In a word, the solution to our cyano problem was a "storm".

The idea behind the storm is to stir up the detritus from the rock, live sandbed and corals, and export it. Since our skimmer had not been fully effective removing the phosphate generated by deteriorating animal waste, we decided to use short term mechanical filtration during the "storm".

The "storm' is generated by repeated jets of water created by a turkey baster bought specifically for reef use only.

Mechanical filtration, in our case, was done by adding the fabric-media sleeves to our two Hagen 802 powerhead Quick-Filter attachments.

Once the powerheads were fitted with media, the storm began:

• all rock, coral and sandbed surfaces were gently blasted with the turkey baster. Blasts into the sandbed went about an inch deep, though around the glass were the cyano had grown, blasts went two or three inches deep.
• at first the tank became alarmingly cloudy, but the detritus that was not mechanically removed slowly settled.
• after about an hour or two, the fibre-media sleeves were removed and cleaned. And cleaned, then cleaned some more.
• to remove as much detritus as possible, a whole day was devoted to repeatedly storming, letting the detritus settle, then thoroughly cleaning the media.
• mechanical filtration is not typically used in our reef, so media was cleaned yet again after the final storm, and left to dry before being stored.

Within a week, the cyanobacteria began to reappear, so another full day of storming was held.

Two weeks later, after a small amount of cyano was observed, a morning of storming took place.