Macroalgae Grow Light for Refugiums and Nutrient Reduction in Reef Aquariums


Maintaining low nutrient levels is key to a healthy and algae-free marine aquarium

Some of the most successful reef aquariums employ the use of a macroalgae-filled growth area or refugium for the purpose of nutrient control.

The GRO is a specialized, 20W LED light designed to grow many types of common macroalgaes (i.e. Chaetomorpha) using a specialized light spectrum which maximizes photosynthesis. It plugs directly into any available DC24 port in your Apex ecosystem, or alternatively, it can also be run completely standalone.

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Feedback from Neptune Systems Insiders early adopters:

The Chateomorpha is growing very fast!
The light spread is incredible and bright.
I am impressed and it seems to be outperforming my last light.
Chaeto is thicker and seemingly more healthy than it has been in the past.
Wowsers does this thing grow chaeto!
The GRO made a HUGE difference over my previous light!
Cheato is still growing like a weed.

Read some of their stories in the GRO community forum

Compact, flat, rectangular LED grow light measures 8.7″ X 6.1″ X 1.4″ making it the perfect fit for the smaller refugium compartments in many modern aquariums — as well as those that wish to grow macroalgae in a separate refugium.

84 LEDs in four colors create an evenly distributed spectrum optimized for macroalgae growth. Two key wavelengths for algae photosynthesis are emphasized — 455-460nm and 620-670nm.

Large, rectangular form promotes better algae growth, while reducing nuisance algae from light spillage, as intensity is evenly spread across a refugium area that is almost always rectangular. The GRO can effectively cover a refugium area up to 18″x24″

Round, spotlight style refugium lights, often create uneven spread of intensity. This causes hotspots that lead to algae burning or stunted growth. With the GRO, the 84 LED in a rectangular form factor create even light intensity and no hotspots.

Nuisance algae on in our sumps and on our equipment is normally one of the downsides of using a refugium. Since most refugia are rectangular, the GRO projects light in a similar manner. Also, with its low-power, distributed LED design, the GRO can be placed very close to the water surface further limiting light spillage and therefore nuisance algae.

The GRO is IP64 rated which means splashes and salt spray will not take it down. This means it can safely be placed close to the water surface, maximizing light effectiveness, and reducing wasteful light spillage that often causes nuisance algae in other parts of a system.

Power the GRO using an available DC24 connection in your Apex ecosystem (on Energy Bar 832 or 1LINK module).

If you do not have an available DC24 port, or you wish to use the GRO without an Apex, a power supply is available so it will operate standalone.

An available gooseneck mount comes in two models:  A traditional clamp style mount to attach it to the edge of your sump. And a unique pipe-clamp mount to attach it to your existing plumbing above or behind your sump.

GRO Sump

Reduce Your Nutrients, the Natural Way, with a Refugium

It’s easy! Growing and harvesting macroalgae in a compartment in your sump, or in a full-blown refugium, is the natural way to reduce unwanted nutrients in your reef aquarium. It also creates a home and reproductive area for beneficial micro-fauna that consume waste and provide a food source for corals and fish. Growing macroalgae opposite your normal light cycle (called reverse daylight photosynthesis or RDP) also helps raise and stabilize your aquarium pH.

Only three things are necessary to get started:

1. A sequestered place in your sump or filtration area that has adequate water flow.
2. A “start” of macroalgae such as chaetomorpha – get it online, from a LFS, or from a reefkeeping buddy.
3. A proper light source, like the GRO.

Optimal Light Spectrum, Just Where You Want It

The GRO uses all its power to emit light in two specific wavelengths that are optimized for macroalgae growth – 455-460nm and 620-670nm. This combined with its rectangular shape (have you ever seen a round refugium?) mean that the right light goes right where you need it – and minimizes nuisance algae growth in other areas of your sump due to light spillage.

GRO Spectrum
Plugging In

Easy Plug and Play Setup

Remove the GRO from the box, plug it into one of your available DC24 connections on an Energy Bar 832 or 1LINK module, select GRO from the tasks menu, and in just a couple of minutes a step by step wizard will have it set up and scheduled.

Better Macroalgae Growth Using Less Power

It may seem counterintuitive – and possibly even fly in the face of some “experts” – but with far less power than its competitors, the GRO promotes thick, healthy, and abundant macroalgae growth. The GRO does this by using 84 low-powered LED, selected for optimal macro algae growth, and spreads them evenly across a wide, rectangular area. This enables the GRO to be placed very close to the macroalgae and increase its efficiency while minimizing wasteful light spillage.

GRO Bottom

Shape Matters!

Nearly all other refugium lights cast light in a round, conical pattern. This is not optimal since a refugium is rarely round, but more importantly light from a round, single source, creates uneven distribution of light – in other words, hot spots that stunt growth or even burn the macroalgae. The pictures here really tell this story. These photos were taken of a large area of macroalgae in a refugium that was lit for 10 months with the GRO on the right side, and one of the most popular and praised refugium lights on the left – notice how the round light stunted growth in the center and created a burned ring of algae.

GRO Mount

Flexible Mounting Options – Literally!

The GRO has two available two different mounting options. Both utilize an 18″ long, flexible gooseneck attached to one of two mounting brackets. One mounting option clamps to a flat edge such as the edge of your sump or support on your stand. The other mount cleverly clamps to a section of your hard plumbing that are 1″ in diameter. (i.e. either 1″ PVC pipe or standard ¾” PVC fittings like elbows or tees). You get to choose which mount best fits your aquarium or refugium set up – or DIY your own!

Water Resistant, IP64 Design

The GRO is rated IP64 so that you can place it very close to the water surface for optimal light effectiveness and water splashes or salt spray will not affect it.

Water Resistance

No Apex or DC24 Port Necessary

Maybe you don’t have a free DC24 port, or even have an Apex at all yet – no worries – with the optionally available 24v power supply, the GRO can be used on any aquarium.


  • Compact LED grow light with 84 LEDs in four colors, two key spectrum ranges for optimal macroalgae growth

  • Large, flat area of illumination promotes better growth as it creates a much more even spread than single, spotlight-style lights.

  • Distributed LED design means no light hotspots that can burn the macroalgae

  • Less light spillage – IP64 water resistance means it can be placed very close to water — reducing the growth of nuisance algae elsewhere

  • Two focused wavelength bands (455-460nm and 620-670nm) for maximum algae photosynthesis

  • Covers a refugium area up to 18”x24”

  • Plugs directly into DC24 connection on an EnergyBar832 or a 1Link module.

  • Dimensions:  8.7″ x 6.1″ x 1.4″ (light panel itself less than 1″ high)

  • Works with any Apex model, including the Apex Classic family.

  • Operates standalone, without an Apex, with the purchase of an optionally available power supply.

  • Mounts using the optionally available, flexible gooseneck, with one of two clamp styles


  • An available, powered, DC24 port in your Apex Ecosystem OR

  • Optional 24V power supply to run standalone


  • GRO LED Light

  • Flexible gooseneck mount

  • One of two mounting brackets (either flat clamp or pipe clamp)