At some point in time there is a high probability a reef keeper will encounter problematic algae. Many times this will occur when a tank is young and does not have a fully established bacteria bed, a period sometimes referred to as the “ugly phase”.

 

But sometimes reef keepers encounter algae in established tanks and battle the problem for many, many months. Algae do rely on light to grow and in extreme cases reef keepers will turn their tank lights off for an extended period of time, usually for three days, to snuff out the problem. Does this really work?

 

3 Day Black Out Reef Tank

 

Well, this method will typically rid a tank of algae when the lights come back on but the key to keeping it away is to identify the source of the problem. If the source is not uncovered, then the algae will return after the black out, guaranteed.

 

3 Day Black Out Alternative – Keep Nutrients in Check

Besides light, elevated nitrate and phosphate levels are the main culprits that feed algae growth and one sound approach to keeping them in check is to lean on basic nutrient export practices such as water changes, strong skimming and GFO (Granular Feric Oxide).


 

In addition to nitrates and phosphates, algae also rely on iron, silicates and other trace elements to grow. Interestingly, just one of these elements has to be low enough to keep algae at bay so it shouldn’t matter if the other elements are high.

 

Turf Algae Reef Tank

 

In most instances it is easiest to limit phosphates by using GFO or another means such as an algae scrubber. However, you do have to be careful when lowering phosphate since corals do require some for their health and well being.

 

Corals Can Fade When all Phosphates are Stripped Out of a Tank

Corals Can Fade When all Phosphates are Stripped Out of a Tank

 

In the end, a three day black will not permanently rid a tank of algae unless the source of the problem is corrected IN CONJUNCTION with the black out. Case in point. I had a bad outbreak of diatoms that was due to an expired filter on my RO/DI unit. I replaced the filter, did a three day black out and ,voila, the diatoms disappeared forever!

 

 

If you are looking for additional insights and information, please explore my many other reef tank and SPS related articles as well as my book, A ReefBum’s Guide To Keeping an SPS Reef Tank: A Blueprint For Success. And you can see all of my reef tank videos online now as well as my Live HD Webcam.

 

Happy reef keeping!