Bulletproof Refugiums – Lighting

Welcome to our series on building bulletproof refugiums! It should come as no surprise that we field a lot of questions about how to build a refugium here at AlgaeBarn. Our customers frequently ask us what they can do to increase the productivity and efficiency of the refugium. So, we decided to create a series of posts on our best tips for building a bulletproof refugium! In this post, we are going to talk about choosing the best lighting for the refugium.

A refugium is widely recognized as the best method for maintaining a constant supply of live food for a reef tank system. The refugium also has a secondary use as a natural filtration system for the entire reef. The honest to goodness truth is if we spend half as much effort in maintaining our refugiums as we do with our displays, we will begin to see the results immediately!

In this post, we are going to focus on answering your questions on refugium lighting. Early reef keepers were very limited in their lighting options. Both fluorescent and metal halide bulbs were the mainstays of lighting fixtures. Today, we have much more efficient and economical options.

For some reef keepers just starting out, it might be a tough decision to earmark funds away from their display tank to grow a little box of algae. At AlgaeBarn, we are serious about refugiums! It may sound cliche, but it truly is an investment in the reef tank’s ecosystem. Live food for fish, inverts, and corals, cleaner water and a healthier reef tank system are what we stand to gain as returns on our refugium investment.

What color light is best for refugiums?

When it comes to lighting for the refugium, full spectrum LED fixtures are the most popular. The blue and red spectrum gives macroalgae the precise wavelengths they need for the most consistent growth rates. Although you can get many varieties of macroalgae to survive just fine on white daylight bulbs, full-spectrum lights generate more robust growth.

In short, almost any LED light designed for coral or plants will work if it has a broad spectrum. Although for optimal growth rates, you will want to choose a more specialized bulb. If you are interested in keeping red algae like Gracilaria or PomPom, you will want a slightly lower light intensity. However, if you are planning on a dense fish population in the display, you might want to set your sights on Clean Chaeto. This green alga can handle much more intense lighting.

But what if you wanted to have a mixture of both red and green macroalgae? Recognize that the quantity of light required will change depending on your choice. Every plant on Earth has a unique minimum lighting requirement. A fixture with an output capable of growing SPS corals would have to be installed to meet the needs Clean Chaeto.

What kind of light do I need for a refugium?

Honestly, there is no straightforward answer to this question. The solution really depends on your reef tank system’s specs and what you want to achieve by adding the refugium. It’s safe to assume that if you’re following this series, one of your goals is to reduce waste compounds in the system. Using full-spectrum lighting is ideal if we want to be successful in growing a wide variety of macroalgae.

Light-emitting diodes (LEDs) are preferred by most reef keepers for growing macroalgae. LEDs don’t generate much heat, so they are good candidates in enclosed spaces like tank stand cabinets. Also, consider the footprint of the available space and the surrounding area. A strip light fixture is the most effective solution if the cabinet is long and narrow. For a narrow, rectangular footprint, we would recommend IM’s ChaetoMax.

The ChaetoMax refugium light packs 45 high-efficiency LEDs, which produce powerful lighting of plant growth-promoting spectrum. ChaetoMax was designed to provide the ideal spectrum of lighting for plant growth within a small space. Another feature is that the ChaetoMax can either be installed vertically or horizontally. Aside from that, it’s built to last with a solid aluminum frame and produces very little heat.

Both square and round shaped refugiums can use a pendant or spotlight style fixture. In most systems with average footprints, we would recommend the Kessil H80 or the Kessil A360X. Kessil H80 is great for systems that are between 12”x12” and 18”x18”. The Kessil H80 incorporates Dense Cluster LED technology, which packs a lot of light into a little space.

Kessil’s A360X fixture is a state-of-the-art LED grow light. It provides more intense light than the average refugium light. Most reef keepers who go with this lamp will attest to seeing rapid macro growth. The spectrum output is adjusted with a single knob, which makes it easy to adjust to any desired range. The A360X can focus light into a pinpoint that can penetrate dense macroalgae growth. This lamp can accommodate larger refugiums ranging in size from 24”x24” to 36”x36”.

How many hours of light does a refugium need?

That depends on what you have in the refugium and what the goals are. Reef keepers are constantly tinkering with combinations of schedules to find the optimal refugium photoperiod. No one has figured out the perfect lighting schedule yet, but we think we have some guidelines to at least get us started in the right direction. In our experience, if the refugium gets at least ten or twelve hours of bright light every day, the microorganisms and macroalgae should thrive.

Recently, there has been an evolution of refugiums focused on optimizing light spectrums for macroalgae growth. Now, more than ever, nutrient export using refugiums is a practical and efficient option as opposed to mechanical and chemical filtration methods of the past.

The light schedule is the primary tool we will use for removing nutrients and waste compounds the refugium filters out. The most efficient nutrient elimination occurs under longer light schedules of up to 18 hours, whereas the least efficient occurs under shorter light schedules of around 6 hours.

Can I run my refugium light 24/7?

Yes! More stable pH levels are another advantage of keeping a refugium. Plants (and macroalgae) use carbon dioxide they get from the air to generate sugar, which stores energy, and biomass. Since the pH of carbonic acid is raised when CO2 is removed from water, this process is used to increase the pH level.

The macroalgae in the refugium absorb carbon dioxide from the water while the light is on. In response, the pH level increases. However, this is something that occurs only during photosynthesis. And photosynthesis only happens during daylight. Therefore, when photosynthesis stops at night, the pH level drops.

By operating the refugium and display tank on opposing photoperiods, we can maintain consistent pH levels. Simply put, the reef keeper is operating the daylight hours of the fuge on an opposing schedule from the display tank. The pH will start to drop as soon as the display lights go out for the night. Especially in reef tanks with a lot of hermatypic corals or giant clams, the pH levels can drop sharply.

Final Thoughts on Refugium Lighting

At this point, we have gone over some key points about refugium lighting. Choosing the right lighting for your refugium is critical but we can help by making it less stressful. Ultimately, the biggest deciding factor will be what your goals are for your reef tank system.

Make sure to visit the AlgaeLab Blog if you’re looking for information on the lighting needs of a particular species of macroalgae.

Do you have other questions on refugium lighting? Drop a comment below and we’ll be glad to help you choose the perfect light for a bulletproof refugium!