How to get rid of Red Slime Algae (cyanobacteria)

June 2012
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How to get rid of Red Slime Algae (cyanobacteria)

Red Slime Algae
by Aquaristic Team

Red slime algae is actually a photosynthetic cyanobacteria. These pesky organisms  generally look like a red or dark purple slime coating that cover your sand bed, aquarium glass and live rock. They feel slimy to the touch and can be brushed off quite easily.  
Causes & Remedy:

  Leaving lighting on for too long 8-9 photoperiod hours is ideal but when there is an outbreak of cyanobacteria, reduce the photoperiod to 4-5 hours temporarily
  Using improper bulbs Use good quality bulbs that produce the right spectrum that corals needs. Combination 10,000 Kelvin and  20,000 Kelvin bulbs are most suitable.
  Not changing old bulbs If the bulbs are more than 6 months old, the light spectrum emitted started to change towards the red spectrum which these cyanobactria thrives in.  
  Carbon Dioxide (CO2) Lack of water movement on the bottom of the tank causes CO2 to accumulate which fuels the photosynthetic bacteria. Increasing water flow generally fix this problem.
  Excess Phosphates (PO4) Phosphate can be introduced into the aquarium through tap water, activated carbon, kH buffers as well as food.  RO/DI top up water, high quality salt mixes and the use of phosphate absorbers can help reduce excess phosphate in your tank. Phosphate reactor is the ultimate solution.
  Excess Nitrate (NO3) Nitrate is the final by-product of the nitrogen cycle, it can naturally build up when sufficient routine water changes is not performed or through overstocking and overfeeding. Perform regular water changes of 10-20% once a week or once per fortnight and vacuuming the sand helps remove nitrate source on the sand bed.
  Hermit Crabs & Snails Most of these inverts don’t actually eat red slime algae, but they do a good job scavenging uneaten food stuck between crevices of the live rock.
  Bottom Stirring Fish Bottom dwelling fish such as sand gobies help turn the sand around and some may even filters the sand in search of cyanobacteria that actually provide them with nutrition. Beware though these fish may need a sufficiently large sand area otherwise they may starve. Most wrasses sleep under the sand which also contributes in stirring the sand.
  Increase flow rate Red slime algae do not stick well thus they normally grow in more stagnant areas in the tank. Adding more powerhead that produces a wide angle current will help get rid of the problem as well as increase the efficiency of the biological filtration in the live rock.
  Uncured Live Rock Newly introduced uncured live rock may cause a sudden nitrogenous waste imbalance in your tank which tend to lead to the occurrence of the red slime algae. Try to siphon off the red slime algae using a small hose to make sure the problem does not continue to spread.
Out of all these problems, high nitrate level is usually the main culprit that causes an infestation of the red slime algae. However, on many occasions, our customers swore that their nitrate level in their tank is 0 or just below 20mg/L. One thing to remember is that these cyanobacteria consumes nitrate at an unbelievable rate. Try removing the red slime algae and you will find that the nitrate reading will start to creep up.
These remedies will not result in an overnight result. It takes time to completely eradicate the problem. There are, however, of the shelf additives such as the Aquamedic Anti-Red™ which will get rid of the problem quickly but these kind of additives may be harmful to sensitive invertebrates and only remove the symptom but not the overall problem. It is a good product to use if you are in a hurry to make your tank looks great within a day or two but careful tank management routine should be maintained thereafter.

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