Saltwater aquarium lights are expensive enough, but now you have to buy a type of light for a thing called a refugium.
Refugiums can be one of the most important parts of reef filtration, and you’ll want to set it up correctly. That means getting the best light possible to help with nutrient export.
Keep reading to find out everything you need to know about refugiums, refugium lighting, and some of the best options available for your saltwater aquarium!
What is a refugium?
In recent years, refugiums have become an essential part of saltwater filtration, especially for reef aquarium setups.
Ideally, refugiums are sections of filtration allotted to removing unwanted nutrients, namely nitrate and phosphate, through biological filtration.
In theory, this would hopefully prevent algae from growing in the display tank and help keep parameters more stable.
Do you need a refugium?
No, you don’t need a refugium to have a successful reef tank. In fact, if set up incorrectly, a refugium can do more harm than good for your tank.
Refugiums can also be added maintenance, expense, and take up space that some hobbyists just don’t have.
However, there are usually more benefits to refugiums than cons if you plan on being in the aquarium-keeping hobby for the long run.
Why do you need a refugium?
Like any other filtration, refugiums are meant to help stabilize your tank and foster an ecosystem.
Refugiums can easily be incorporated into most sump setups, making a refugium an accessible addition for many saltwater enthusiasts.
But how does a refugium work exactly?
A buildup of nuisance algae happens to all of us, and it’s a natural part of aquatic ecosystems. The problem is that these algae can be ugly and can start to interfere with the balance of the system and even cause equipment to malfunction; for reef-keepers, algae can quickly smother prized corals.
Algae grow when there are excess nutrients, like nitrate and phosphate, along with too much light. This algae is self-limiting and will only continue to grow until these nutrients have been depleted.
Algal growth is a problem when it happens in the display tank, but not so much when we can decide where this nutrient uptake happens. You can do this with light and a more desirable species of algae in a refugium setting.
Refugiums can also be used to regulate pH. This is done by running the refugiums’ lights at night while pH is naturally decreasing.
The algae will continue to grow when the light is on, releasing oxygen into the water and ultimately buffering the pH back up.
If this is confusing, we will go more into detail about photosynthesis and pH later.
Copepods, amphipods, etc.
Refugiums are one of the best ways to farm live foods, like copepods, amphipods, and other microfauna. It can be especially beneficial if you have live-food-dependent fish, like mandarin gobies.
Refugiums can also be used to house any cleanup-crew-members-gone-bad that might have started picking at corals, like various crab species. Refugiums can also be used to keep fish fry safe while they mature.
How to set up a refugium
Refugiums are easy to set up and generally inexpensive. Many hobbyists get the wrong idea that refugiums require specialized equipment that usually carries a hefty price tag, but this is not true.
As with anything in this hobby, a refugium can be as expensive or as inexpensive as you would like. The most costly and top-quality refugium light fixture might not be the best thing for your tank after all!
The first thing you will have to decide is where you want to keep your refugium. It doesn’t need to be a large space, but it should be easily accessible for maintenance with enough room for an overhead tank light.
Some possible places for your refugium are in your sump, in a hang on the back filter, or another container in or outside the aquarium.
Next, you will want to pick which types of algae you want to harvest in your refugium. Here are some of the most popular algae choices, along with some other alternatives:
- Chaeto (Chaetomorpha spp.) is the most popular and some of the easiest algae to maintain.
- Caulerpa spp. have a more appealing appearance but can be challenging to control their spread.
- Pest corals. Some hobbyists like to keep ‘pest’ corals in their refugiums, like Kenya trees (Capnella sp.) and Xenia (Xenia spp.). These corals grow fast but can easily spread to the main display aquarium if left unregulated.
- Mangroves are not as efficient with nutrient export as the other algae listed but can make an interesting addition to the aquarium. Mangroves can become difficult once they start to get larger.
Some hobbyists keep pieces of live rock in their refugiums as a foundation for algae and for copepods to hide, but this is unnecessary and can catch excess detritus; a substrate is also optional.
Finally, you will need to consider lighting. Algae is photosynthetic, meaning it uses a light source to convert carbon dioxide and water to create glucose (sugar) and oxygen.
Luckily, this algae doesn’t need the light intensity of your display reef tank, but some preferred choices are available on the market.
This light should be designed for plants instead of corals, which means that the active spectrum output should be geared more towards reds and blues. A good spectrum will emit a pink light.
This light should be turned on between 6-18 hours per day depending on nutrient levels in the tank; a more extended photoperiod will take up more nutrients.
It is also important to think about where you will want to put this light. Refugiums are usually cramped spaces, and you might not have the overhead to fit a light comfortably.
Luckily, some water-proof submersible options are available, which can give you peace of mind regarding any electrical problems.
Best refugium lights
As with anything in the aquarium hobby, you can spend as little or as much money on equipment as you want; of course, quality comes with a price, though some things don’t necessarily need to cost a fortune.
A refugium light is one of the things where more expensive lights don’t necessarily mean better. For the most part, a decent light programmed to grow plants will also grow algae.
Here are some of our top picks considering price, size, intensity/spectrum, and customer reviews.
ACKE LED Grow Lights Full Spectrum, Plant Light, Growing Lamps 12W for Indoor Plants, Hydroponics
Are you looking for an efficient refugium light on a budget? The ACKE LED Grow Lights Full Spectrum is used by many aquarium-keepers, even though it lacks a recognizable brand name.
Don’t be discouraged, though; this light delivers a lot of power for its reasonable price.
The 12W ACKE LED Grow Light is programmed with red (630 nm and 660 nm), blue (460 nm), and white (2700K) lights to encourage photosynthesis. These lights are labeled as waterproof and come with an adjustable light bracket for easy placement.
With proper upkeep, this ACKE LED refugium light can last 50,000 hours. However, hobbyists have found that it can make electrical noises and give off excess heat at times. The pre-installed bracket can also be inconvenient, and the entire system has been known to fail soon after purchase.
Though labeled as waterproof, it is not meant to be constantly submerged. Hobbyists should be aware that the power adapter is relatively large, which might take up valuable space on an extension cord.
What we like:
- Dependable, simple growing light that many hobbyists use for healthy growth of macroalgae
- Compact size and long lifespan
- Waterproof to a point
What could be better:
- Limited controls for intensity or spectrum
- The bracket is poorly designed
- Common to overheat and fail
- Large power adapter which can take away a lot of space from the outlet/extension cord
Tunze Eco Chic Refugium 8831
- We recommend using the Tunze Eco Chic Refugium Light 8831 as a refugium light. This light is submersible and can easily fit into the back chamber of a nano tank or in a sump. You can put the light in…
- Though we champion this unique light as a refugium light, it could also be used as a planted tank light for aquariums up to 15 gallons.
- Wattage: 9 watts
The Tunze Eco Chic Refugium light is a submersible light for refugiums from a dependable aquarium brand.
Having something electrical submerged constantly in your fish tank is an excellent reason to be worried, and you want to make sure that you can trust the equipment you’re using.
This Tunze refugium light is incredibly trustworthy and has some benefits that an overhead or cheap refugium light doesn’t:
- A submersible light is easy to fit in cramped spaces where there might not be room above the refugium for a complete light unit.
- The light output is more concentrated and won’t spill into other parts of the sump or out of the container for better macroalgae growth. Overhead lights can have a lot of unwanted spread, leading to algae growing in unwanted spots. A submerged light can be placed directly in front of the macroalgae for best growing results.
The Tunze Eco Chic Refugium light measures 12 L x 0.98 W x 0.66 H inches (30.5 x 2.5 x 1.7 cm) and is 9 Watts; this light can sometimes be longer than expected, so make sure to measure the area you want to place it.
What we like:
- Submersible design that is space-saving and provides more direct light
- Dependable aquarium brand
- Versatile mount for best placement
What could be better:
- Sometimes an awkward length for some refugium setups
- Limited control over intensities and settings
- Moderately priced
Innovative Marine ChaetoMax Refugium LED Light
- Designed for Sumps and AIO Aquariums. Fits all Desktop Model Nuvo Fusion Aquariums
- 45 x 0.2W 60mA LEDs: 5 – 420nm BLUE. 10- 470nm VIOLET. 10- 630nm MAGENTA. 20 – 660nm RED
- Small form factor (DIMS: 6.7” x 1.85” x 0.39”)
The Innovative Marine ChaetoMax Refugium LED Light is designed specifically for Nuvo Fusion aquariums but can be modified for universal use with other tanks.
This light comes in 9W or 18W with double the light. It is installed with (5) 420 nm blue, (10) 470 nm violet, (10) 630 nm magenta, and (20) 660 nm red lights; the number of lights is doubled on the more powerful option. CHICKEN
The Innovative Marine ChaetoMax light has little to no heat transfer and comes with a bracket mount. However, these lights can sometimes be underpowered and are not considered waterproof.
They also do not include a timer and can be expensive considering what they offer.
What we like:
- Different power options to fit different refugium sizes
- Good spectrum for the growth of macroalgae
- Included mounting bracket
What could be better:
- Not waterproof
- Generally underpowered and overpriced
- Timer not included
Kessil H160 Tuna Flora LED Refugium Grow Light
- Kessil H160 Tuna Flora LED Refugium Grow Light is a horticultural light that is fine tuned for photosynthesis and uses the same platform as the Kessil A160. There are no white LEDs in the Kessil H160,…
- Weight: .9 pounds (the power supply weighs an additional .9 pounds). Dimensions: 4-3/4″ (including knobs) X 2.5″ Diameter.
- 40 Watts: Effective light equal to a 175 Watt metal halide
If you are looking to go all out on your refugium setup, then the Kessil H160 Tuna Flora LED Refugium Grow Light is top of the line.
These lightweight, compact LED lights are 40 Watts (equivalent to a 175 Watt metal halide light) and feature only red and blue light for the best photosynthetic response.
These lights have four settings:
- Blue – targets stem extension and expansion of the plant
- Grow – designed to facilitate overall growth
- Bloom – used during the reproductive stage of the plant for productive flowering
- Red – increases overall productivity and facilitates root and tissue growth
It is important to consider the depth of the refugium over which you plan on placing your Kessil H160 as the Kessil H380 offers great deeper water penetration and might be a better choice of light.
Overall, this light performs spectacularly well. The Kessel H160 is quiet, provides minimal heat, and works well with larger saltwater systems.
This light does not include a mounting bracket and can have an enormous spread.
What we like:
- Several growing settings for complete control of output
- Lightweight and produces minimal heat
- Optimal plant growth light spectrum
What could be better:
- Does not include a mounting bracket
- Very expensive
AI Prime Fuge
If you are already running Aquaillumination (AI) lights on your main display, you might as well use the same lights for your refugium!
The AI Prime Fuge delivers 15 Watts of PhytonRed, 13.4 Watts of Red, 13.4 Watts of Cool White, and 4.2 Watts of UV with 80-degree lenses. You can easily control these intensities with a smartphone application.
These refugium lights are specifically designed for promoting rapid and healthy macro algae growth. While the AI Prime Fuge is proven to deliver results, it does not include mounting material.
What we like:
- Dependable reef aquarium lighting
- Precisely calibrated with photosynthesis in mind
- Easy-to-use smartphone application
What could be better:
- Very expensive
- Does not include mounting material
Can you leave a refugium light on all the time?
As we mentioned before, how long you leave your refugium light on determines how many nutrients are taken up in the system. There is some debate about whether or not a refugium runs best with constant light or with breaks, though.
To understand this more, we need to know how photosynthesis works.
Photosynthesis is a complicated process. The main goal is for the plant to make food. This is done with carbon dioxide, water, and plenty of light, resulting in glucose and oxygen.
But how does this happen?
There are two main steps to photosynthesis: light-dependent and light-independent (also known as the Calvin cycle) reactions. As we’ll see, “light-independent reactions” is a misnomer.
In light-dependent reactions, the plant captures energy from the sun or another artificial light and stores it while taking up water. Oxygen is created in this process and released back into the atmosphere.
In the light-independent reaction, carbon dioxide is used along with the energy captured to create sugar. This process does not require light, though it can also happen when light is present.
Photosynthesis in the refugium
So what does this mean for your macroalgae?
You can have light-dependent and light-independent reactions regardless of whether the light is on all the time or if only for a set period.
Dependent versus independent reactions isn’t the argument. Instead, hobbyists question the efficacy of those reactions under constant light conditions. Like other animals, plants have a circadian rhythm. This means that they use a sleep-wake cycle to regulate physiological processes.
This sleep-wake cycle is primarily used to determine environmental factors, like seasons and other stressors for which the plant needs to prepare or adapt.
It has been observed that some plant species need this circadian rhythm to grow properly; varying times of sunrise and sunset between days have also shown ill effects.
While this is true, some hobbyists have macroalgae overflowing their tanks on a 24/7 lighting schedule. There don’t seem to be any detrimental effects of running a light all the time, though this can become quite costly and runs the risk of overheating or short-circuiting your equipment.
Also, consider other species in the refugium, like copepods, that are dependent on a sleep-wake cycle.
Reasons for keeping your refugium light on 24/7
If you’re okay with spending a little more every month on electricity and accept the risk factor, then there are a few benefits to keeping a refugium light on all the time.
The main benefits are pH regulation and to prevent some species of macroalgae from reproducing and spreading throughout the rest of the refugium and the display tank.
There’s water chemistry, and then there’s understanding how your aquatic system is working together as an input and output system.
Thinking back to photosynthesis, we understand that plants take up carbon dioxide from the water, directly causing pH to rise.
Carbon dioxide becomes carbonic acid when dissolved in water, which is acidic. pH is a measurement of acidity and basicity, with acidic values being below 7.0 and basic values being above 7.0; 7.0 is neutral pH.
As more carbonic acid is removed from the water by macroalgae, this causes the pH to become more basic and move higher up on the pH scale.
At night, photosynthesis does not occur in your saltwater aquarium. Instead, fish, invertebrates, and other living microfauna respire introducing carbon dioxide back into the system. However, there are no photosynthesizers to process this carbon dioxide, so the tank becomes more acidic, and pH drops.
This fluctuation in pH is entirely normal and usually does not affect the life inside your tank. However, some hobbyists choose to run their refugium light all the time to lessen the amount that pH swings between day and night.
Another alternative would be to run the refugium lights at night instead of during the day on a reverse schedule.
Some species of algae are dependent on the sleep-wake cycle for reproduction, namely members of Caulerpa. This alga can reproduce via sporulation, quickly leading to algae growing where you don’t want it to be.
If this alga makes it into your display aquarium, it can proliferate and take over some corals. More importantly, it can start taking nutrients from your corals if left to grow freely.
As mentioned before, plants use daylight and nighttime to regulate their physiological processes. If the refugium light is left on all the time, it is believed that this will help your algae reproduce.
Alternatives to refugiums
A refugium isn’t necessary, but you still might want a way to keep your nutrients under control. There are some alternatives, including protein skimmers and algae scrubbers.
Some hobbyists choose to run a protein skimmer together with an algae scrubber or refugium, but running an algae scrubber and refugium together is usually overkill. It will strip your tank of too many nutrients.
If all else fails, you can always replace a protein skimmer, algae scrubber, or refugium with good old water changes!
If starting a saltwater aquarium or a reef tank, a refugium is something you should consider. These self-contained biological filters can help remove excess nutrients, keep oxygen levels high, and regulate pH levels.
Some tried-and-true macroalgae species work best for a refugium, like chaeto, but other corals and invertebrates can be kept as well.
If you have any questions about refugiums, saltwater, or freshwater aquarium filtration, or have had a bit of experience setting up your own custom filtration, don’t hesitate to leave a comment below!