Dosing Nitrates Cyanobacteria

Will a 3 Day Black Out Eliminate Algae in a Reef Tank?

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.

pale coral

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!

Additional Resources

If you would like some help with a new tank build, including help designing a custom aquarium, or help re-configuring your current setup then you can visit this page for more information. And if you are looking to add some equipment, I do sell GHL, Pax Bellum, Reef Octopus Calcium and Kalk Reactors and Royal Exclusiv products, including Dreamboxes, which is the equipment I use and recommend. I also sell Reef Brite metal halide and LED fixtures as well as Maxspect & IceCap Gyres.

As for additional insights and information, please explore my many other reef tank and SPS related articles as well as my YouTube channel. For an even deeper dive into reef tank care you can check out my Reef Keeping Master Class. This online course is an immersive and one of a kind educational tool designed to help reef aquarium hobbyists build and maintain a beautiful SPS reef tank. The course is a series of video presentations with some supplemental video from my YouTube channel. There are also quizzes to help students retain and understand the information presented in the course.

Need some frags…..I can help with that as well 🙂 Please visit my SPS Frag store to see what is available.

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