𝐇𝐚𝐫𝐧𝐞𝐬𝐬𝐢𝐧𝐠 𝐀𝐥𝐠𝐚𝐞 𝐏𝐨𝐰𝐞𝐫:

𝐄𝐯𝐞𝐫𝐲𝐭𝐡𝐢𝐧𝐠 𝐘𝐨𝐮 𝐍𝐞𝐞𝐝 𝐭𝐨 𝐊𝐧𝐨𝐰 𝐀𝐛𝐨𝐮𝐭 𝐀𝐥𝐠𝐚𝐞 𝐓𝐮𝐫𝐟 𝐒𝐜𝐫𝐮𝐛𝐛𝐞𝐫𝐬

Introduction

Way back when—probably a Wednesday in the mid-1980s—Dr. Walter Adey, a marine biologist, had a groundbreaking idea. While studying natural coral reef systems at the Smithsonian Institution, he realized that algae, often dismissed as a pesky nuisance, could be harnessed as a powerful nutrient export tool. And thus, the algal turf scrubber (ATS) was born, forever changing the way we approach reef tank filtration.

Now, I have to confess: I absolutely love algae scrubbers. They’re brilliantly simple, surprisingly effective, and a perfect example of using nature’s own processes to make your reef tank thrive. From stabilizing nutrients to reducing nuisance algae, ATS systems do so much with so little—it’s hard not to be impressed. I can’t wait to dive into why these scrubbers are such a game-changer and how you can use them to make your tank the envy of the reefing world. Let’s get scrubbing!

How Algae Scrubbers Work: The Science (Yay, Science!)

Let’s talk about what really makes algae scrubbers tick—not just the basics of the nitrogen cycle, but the elegant chemistry and biology that transform these green growth machines into nutrient-export powerhouses. Algae scrubbers aren’t just "another filter"; they’re like an ecosystem in overdrive, using every trick in nature’s playbook to restore balance to your tank.

Algae are more than passive sponges for nitrates and phosphates—they’re active chemical factories, fine-tuned by millions of years of evolution to extract, process, and even compete for resources. Here's the deeper dive:

Nitrate Reduction:

• Algae don’t just "absorb" nitrate—they convert it into amino acids and proteins, which they use to build cellular structures. By pulling nitrate out of the water column, algae effectively hijack the nitrogen cycle to fuel their own growth. It’s a tactical move that starves nuisance algae of the same resources.

Phosphate Sequestration:

• Phosphorus, the elusive nutrient that limits growth in many systems, gets locked into algae cells as part of ATP (adenosine triphosphate)—the energy currency of all living things. This makes your scrubber a dynamic player in the battle against phosphate accumulation, which fuels algae blooms in the display tank.
• Bonus: Unlike chemical binders like GFO (granular ferric oxide), algae don’t just trap phosphates—they recycle them into useful compounds.

Why ATS Work So Well

Here’s where things get really interesting: algae on your scrubber don’t just grow—they dominate.

Chemical Warfare:

• Algae are known to release allelopathic compounds—subtle chemical signals that inhibit the growth of competing organisms, including nuisance algae in your display tank. This "offense is the best defense" strategy allows your scrubber algae to monopolize nutrients.

Space and Resource Monopolization:

• Scrubber algae outcompete nuisance algae by claiming resources at the source. They create a nutrient vacuum, depriving undesirable species of the raw materials they need to thrive.

Key Components of an ATS

Water Flow

A pump or gravity-fed system ensures water consistently moves across the scrubber’s surface. Proper flow delivers nutrients like nitrates and phosphates to the algae while preventing detritus buildup. For waterfall scrubbers, aim for an even cascade; for upflow scrubbers, create gentle turbulence with air bubbles.

Light Source

High-intensity LED grow lights, particularly in the red spectrum (~660 nm), drive algae growth by optimizing photosynthesis. Blue light (~450 nm) may also be used to stimulate accessory pigments. Position the lights close enough to the screen for effective coverage, with a photoperiod of 12–16 hours daily.

Growth Surface

A roughened mesh or textured mat provides an anchor for algae to grow. The slight texture allows algae to attach securely and spread efficiently. Plastic canvas or specialized scrubber screens are common choices due to their durability and ease of cleaning.

Types of ATS

1. Waterfall Algae Scrubbers:

• They Work: Water flows down a vertical screen, illuminated by grow lights.

• Best For: Medium to large tanks

• Pros: Efficient at nutrient removal, easy to maintain.

• Cons: Requires more space and plumbing.

2. Upflow Algae Scrubbers (UAS):

• • How They Work: Air bubbles push water upward over a submerged growth surface, lit from above.
  • Best For: Smaller tanks or limited sump space.
  • Pros: Compact, quieter operation.
  • Cons: Slower nutrient export compared to waterfall models.

3. Horizontal Algae Scrubbers:

• • How They Work: Water flows across a flat screen in a tray-like structure.
  • Best For: Large tanks with room for horizontal installations.
  • Pros: Offers even light distribution and high growth potential.
  • Cons: Space-intensive and harder to retrofit.

Lighting for Algae Scrubbers: Spectrum, Intensity, and Placement

Lighting is the lifeblood of an algae scrubber, as it powers photosynthesis and drives algae growth. Choosing the right light and positioning it correctly can make or break your scrubber’s efficiency.

Optimal Spectrum

• Red Spectrum (~660 nm): Red light is the most effective for algae growth because it aligns with the peak absorption range of chlorophyll a, the primary pigment in algae. Most scrubbers use high-intensity red-spectrum LEDs to maximize photosynthesis.
• Blue Spectrum (~450 nm): Some scrubbers incorporate blue light to stimulate accessory pigments, which can enhance growth rates and promote a healthier, more diverse algae mat.
• Balanced Spectrum: While red is the workhorse, a small addition of blue or white light can ensure robust growth and prevent spectral limitations.

Intensity and Duration

• High-Intensity Lighting: Algae thrive under bright light, so choose LEDs specifically designed for grow systems. The wattage and lumen output should match the size of your scrubber.
• Photoperiod: Most scrubbers operate on a 12–16 hour light cycle to simulate optimal growing conditions. For faster algae growth, some advanced setups run 24/7 lighting, but this depends on your tank’s nutrient levels and the scrubber’s capacity.

Light Placement

• Proximity to Screen: Position the light close to the growth surface, typically 1–4 inches away, to ensure strong illumination. Avoid placing it too far, as light intensity diminishes with distance.
• Coverage: Ensure even light distribution across the entire scrubber surface. Uneven lighting can result in patchy algae growth and reduced efficiency.
• Heat Management: Place the light where it won’t overheat the water or equipment. Many modern scrubbers use LEDs with minimal heat output, but it’s still a factor to consider in enclosed spaces.

1. Waterfall Algae Scrubber

• • • Light Placement: Above or to the side of the growth screen, outside the water.
    • Why: The algae grow on a vertical screen, and the water cascades over it. Positioning the light outside the water ensures it remains dry and provides even coverage across the screen.

Tamara's Pro Tip: Use reflectors or dual-side lighting for larger screens to ensure even growth on both sides.

2. Upflow Algae Scrubber (UAS)

• • • Light Placement: Inside the water, directly illuminating the growth surface.
    • Why: In a UAS, the algae grow on a submerged screen, so the light must be placed underwater to reach the algae effectively. Most UAS systems use waterproof LEDs or lights encased in a protective housing.

3. Horizontal Algae Scrubber

• • • Light Placement: Above the water, illuminating the flat surface of the scrubber.
    • Why: The algae grow on a horizontal screen, and placing the light above ensures uniform coverage. Some systems use a transparent lid to protect the light from splashes.

Tamara's Pro Tip: Use high-intensity LEDs to compensate for any light diffusion caused by splash guards or covers.

Flow Requirements

Flow isn’t just about "keeping things moving"; it’s a critical factor in how algae scrubbers function. Algae need two things to grow efficiently: nutrient delivery and waste removal.

Nutrient Uptake Zones:

• The surface of your scrubber is an active exchange site. Nutrients in the water column diffuse into the algae’s cells, but this process relies on constant replenishment of nutrient-rich water. Without flow, the algae essentially "starve" despite high nutrient levels elsewhere in the tank.

Self-Cleaning Action:

• Alternating currents across the scrubber prevent detritus buildup, which could otherwise block light and smother algae. The dynamic flow also mimics natural reef environments, where wave action enhances growth.

Benefits of Using an Algae Scrubber

1. Nutrient Control

An algae scrubber excels at reducing nitrates and phosphates, the two key nutrients that fuel unwanted algae growth in your display tank. By cultivating algae on the scrubber, these nutrients are absorbed into the algae’s biomass, which is then removed when harvested. This keeps nutrient levels in check, preventing nuisance algae outbreaks and maintaining water quality over time.

2. Natural Filtration

Algae scrubbers mimic the natural filtration processes found in reef ecosystems, where algae grow on rocks and other surfaces, absorbing nutrients from the water. Unlike chemical filtration methods that rely on synthetic media, algae scrubbers use nature’s methods, providing an eco-friendly and chemical-free solution for nutrient management.

3. Supports Coral Growth

By maintaining nutrient levels within an ideal range, algae scrubbers create an environment that supports healthy coral growth and vibrant coloration. Excess nutrients can lead to stress and reduced growth in corals, while too few nutrients can cause corals to starve. Algae scrubbers strike a balance, ensuring your corals have everything they need to thrive.

4. Algae Reduction

Nuisance algae in the display tank are often caused by excessive nutrients. Algae scrubbers compete directly with these problem algae by monopolizing resources like nitrates, phosphates, and light. As a result, nuisance algae are starved out, leaving your display tank cleaner and more visually appealing.

5. Oxygen Production

Algae photosynthesis doesn’t just remove nutrients—it also produces oxygen, which dissolves into your aquarium water. This extra oxygen improves the overall health of your tank inhabitants, enhancing the environment for fish, corals, and other organisms, especially in systems with high biological loads.

6. Cost-Effective

While there’s an initial investment in setting up an algae scrubber, the long-term benefits make it highly cost-effective. Once established, algae scrubbers reduce or eliminate the need for expensive filtration media like GFO (granular ferric oxide), saving money on consumables while providing a sustainable nutrient management solution.

Potential Drawbacks and Challenges

1. Space Requirements

Algae scrubbers often require dedicated space in your sump or as an external setup. This can be a challenge for aquariums with limited room or compact sumps. While there are smaller models like upflow algae scrubbers (UAS) for nano tanks, larger systems may need substantial clearance for the scrubber and lighting components.

2. Maintenance

Algae scrubbers are not "set it and forget it" devices. To maintain efficiency, you’ll need to harvest algae regularly, typically every 1–2 weeks, to prevent overgrowth and promote new growth. Cleaning the scrubber screen and checking for clogs in water flow are also essential to keep the system running smoothly. If neglected, algae can die off and release nutrients back into the tank.

3. Initial Costs

A high-quality algae scrubber, whether commercially made or a well-built DIY version, can involve a significant upfront investment. Costs include the scrubber unit, high-intensity LED grow lights, and possibly a dedicated pump. While the long-term savings on media like GFO are notable, the initial expenses may deter budget-conscious hobbyists.

4. Light Pollution

Bright LED grow lights, especially those in the red spectrum, can spill into the surrounding area if the scrubber isn’t enclosed. This might be an issue in display setups where the sump is visible or in rooms where excess light might become a distraction. Some hobbyists mitigate this by using light-blocking covers or positioning the scrubber in a closed sump cabinet.

Step-by-Step Guide to Setting Up an Algae Scrubber

Step 1: Choose Your Algae Scrubber Type

Decide on the type of scrubber based on your tank size, setup, and goals:

• Waterfall Scrubber: Best for medium to large tanks.
• Upflow Algae Scrubber (UAS): Ideal for nano tanks or limited sump space.
• Horizontal Scrubber: Great for large tanks with ample sump room.

Step 2: Gather Materials

For a DIY scrubber, you’ll need:

• A plastic mesh screen (rough surface for algae growth).
• Submersible LED grow lights (red or full spectrum).
• PVC pipes and fittings (for water flow and structure).
• A small pump (adjustable flow recommended).
• Zip ties or clips to secure components.
• A bucket or container for testing the setup.

There are SO many amazing videos of how to set up a DIY scrubber on YouTube I will let you stick with the pros on that one :)

For a commercial scrubber, follow the manufacturer’s installation guidelines. Most kits come with all necessary components.

Step 3: Install the Growth Surface

• DIY: Cut the plastic mesh screen to size and roughen the surface using sandpaper for better algae adhesion.
• Secure the screen to the PVC frame using zip ties.
• Position the frame so water will flow evenly across the mesh (for waterfall scrubbers) or upward through it (for UAS).

Step 4: Set Up the Water Flow

• Connect the pump to the scrubber using tubing or PVC.
• Adjust the flow rate:
  • Waterfall Scrubber: Aim for a gentle, even cascade over the screen.
  • UAS: Ensure bubbles rise uniformly through the screen.

Step 5: Add Lighting

• Attach LED grow lights on both sides of the growth surface (for waterfall and horizontal scrubbers) or above the screen (for UAS).
• Ensure the lights are close enough to promote algae growth but not so close they overheat.

Step 6: Test the Setup

• Run the system in a bucket or directly in your sump.
• Check for:
  • Even water flow across the screen.
  • Proper light placement without light spillover into the display tank.
  • No leaks or blockages.

Step 7: Install in Your Tank

• Place the scrubber in your sump or an external area where it can drain safely back into the tank.
• Secure all components and ensure easy access for maintenance.

Step 8: Maintenance Routine

• Harvesting Algae: Remove the algae every 1–2 weeks to maintain growth efficiency.
• Cleaning the Screen: Gently scrape off algae buildup to avoid clogging.
• Checking Flow and Lights: Ensure the pump and LEDs are functioning properly for consistent performance.

Comparison of Popular Commercial Algae Scrubber Models

There are lots of brands and models. This is by no means an exhaustive list. Also, not all of the websites were user friendly so for those ones, I put BRS as the link to give more information on the product, but I am not affiliated with them.

Tips for Success

• Monitor Growth: Healthy algae should appear bright green. Brown or slimy growth indicates issues with flow, lighting, or nutrients.
• Regular Cleaning: Harvest algae frequently to maintain efficiency.
• Complementary Equipment: Pair your scrubber with a protein skimmer for optimal filtration.

Can You Run an ATS and Protein Skimmer Together?

Absolutely! Algae scrubbers and protein skimmers can work in harmony to provide comprehensive filtration for your reef tank. Each system targets different aspects of nutrient control, making them an ideal duo for maintaining water quality.

How They Work Together

• Algae Scrubber: Removes dissolved nutrients like nitrates and phosphates by growing algae, which consume these compounds as they thrive on the scrubber's surface.
• Protein Skimmer: Extracts organic waste (fish waste, uneaten food, etc.) before it has a chance to break down into nitrates and phosphates, reducing the nutrient load that the scrubber has to process.

By combining these methods, you tackle nutrient control both at the source (via the skimmer) and at the dissolved stage (via the scrubber). This layered approach provides excellent water quality and minimizes the risk of nuisance algae in your display tank.

Placement When Using Both:

• Position the skimmer upstream from the algae scrubber in your sump. This ensures the scrubber receives cleaner water, free from particulates that could clog the screen.
• Keep the two systems in separate sump compartments or spaced apart to avoid operational interference.

Types of Algae Commonly Found on an Algae Scrubber

Algae scrubbers are designed to promote the growth of specific types of algae that efficiently remove nutrients (nitrates and phosphates) from aquarium water. While the exact types of algae that grow can vary based on tank conditions, lighting, and nutrient levels, here are the most common varieties:

1. Green Hair Algae (GHA)

• Description: Fine, filamentous algae with a vibrant green color.
• Why It Grows: Thrives in nutrient-rich water with adequate lighting.
• Role: Green Hair Algae is the most effective type for nutrient export. It grows quickly, absorbing nitrates and phosphates efficiently, and is relatively easy to harvest.
• Preferred Conditions: Moderate to high light intensity and consistent water flow.

2. Turf Algae

• Description: Coarser and thicker than Green Hair Algae, often forming dense mats on the scrubber surface.
• Why It Grows: Prefers high-nutrient environments and strong water flow.
• Role: Excellent for long-term nutrient export due to its durability and ability to grow in various tank conditions.
• Preferred Conditions: Strong flow and slightly rougher growth surfaces to anchor the algae.

3. Red Algae (Rhodophyta)

• Description: A reddish or brownish hue, often slimy or stringy in texture.
• Why It Grows: Tends to appear in tanks with lower light intensity or in shaded areas of the scrubber.
• Role: While not as efficient as Green Hair Algae or Turf Algae, red algae still contribute to nutrient export.
• Preferred Conditions: Low to moderate light and slightly higher nutrient levels.

4. Diatoms (Brown Algae)

• Description: Dusty brown or golden algae that form a thin film.
• Why It Grows: Often appears in new or recently cleaned scrubbers where silicates are present in the water.
• Role: Less effective for nutrient export and usually temporary until other algae types dominate.
• Preferred Conditions: Lower light and higher silicate levels.

5. Cyanobacteria (Blue-Green Algae)

• Description: Slimy, often red, green, or black, and tends to grow in areas with stagnant water flow.
• Why It Grows: Usually a sign of insufficient flow or lighting imbalance.
• Role: Cyanobacteria is not beneficial for nutrient export and can be problematic if it overtakes the scrubber.
• Preferred Conditions: Low flow and high nutrient levels.

Troubleshooting Your Algae Scrubber

Even the best algae scrubbers can encounter hiccups. Here’s a troubleshooting guide to address common issues and keep your scrubber performing optimally:

1. Uneven Algae Growth

Symptoms: Some areas of the scrubber grow thick, healthy algae while others remain bare.
Causes:

• Inconsistent water flow across the screen.
• Uneven lighting or light placement too far from the screen.
• Screen surface not properly roughed up for algae attachment.
  Fixes:
• Adjust the pump or plumbing to ensure water flows evenly across the entire screen.
• Reposition lights for even coverage or replace dim or ineffective bulbs.
• Roughen the screen with sandpaper to improve algae adhesion.

2. Slime or Cyanobacteria Growth

Symptoms: Slimy, reddish, or brown algae overtakes the scrubber instead of desirable green or turf algae.
Causes:

• Insufficient water flow or stagnant areas on the screen.
• Imbalanced lighting spectrum, often too much blue light.
• Excess nutrients like silicates in the water.
  Fixes:
• Increase flow across the screen and ensure no stagnant areas.
• Use red-spectrum grow lights designed for algae scrubbers.
• Test for silicates and reduce them with media like GFO or silicate removers.

3. Lack of Algae Growth

Symptoms: Little to no algae growing on the scrubber after several weeks.
Causes:

• Insufficient nutrients (nitrates or phosphates too low).
• Screen not properly conditioned.
• Light intensity too low or spectrum unsuitable.
  Fixes:
• Test tank water for nutrients and, if too low, reduce nutrient export from other systems like skimmers or GFO reactors.
• Condition the screen by allowing light exposure for a few days before use.
• Upgrade to higher-intensity grow lights with a red spectrum.

4. Algae Growth Too Fast

Symptoms: Algae clogs the scrubber quickly, requiring frequent cleaning (e.g., every few days).
Causes:

• Excessively high nutrient levels in the tank.
• Lighting intensity too strong or left on too long.
  Fixes:
• Reduce feeding or perform water changes to lower nutrient levels.
• Adjust the light schedule to 12–16 hours per day.

5. Water Flow Issues

Symptoms: Water spills over the sides or creates dead zones on the screen.
Causes:

• Clogged pump or screen.
• Improper screen placement or tilt.
  Fixes:
• Clean the pump and screen regularly to maintain flow.
• Reposition the screen to ensure proper alignment with the water flow.

Common Myths About Algae Scrubbers

Myth 1: Algae Scrubbers Replace All Other Filtration

Reality: While algae scrubbers are excellent for nutrient export, they do not remove particulates or dissolved organics like a protein skimmer. They work best as part of a holistic filtration system alongside skimmers, mechanical filters, and other tools.

Myth 2: Algae Scrubbers Will Starve My Corals

Reality: Properly sized scrubbers remove excess nutrients without completely stripping the tank. In fact, stable nutrient levels benefit corals by preventing nuisance algae competition and maintaining better water clarity.

Myth 3: Algae Scrubbers Are Only for Reef Tanks

Reality: Algae scrubbers are highly effective in fish-only systems, predator tanks, and even freshwater setups, as they manage nutrients across various tank types.

Myth 4: Algae Scrubbers Are High Maintenance

Reality: While regular harvesting is required, most scrubbers only need cleaning every 1–2 weeks. With proper setup and flow, they are relatively low-maintenance compared to other filtration systems.

Myth 5: Any Algae Growth on the Scrubber Is Good

Reality: While green hair algae and turf algae are ideal, slime algae or cyanobacteria indicate issues with flow, lighting, or water parameters. Not all algae growth is equally beneficial.

FAQs About Algae Scrubbers

Q: Do I need to add macroalgae to my scrubber?

A: Nope! An algae scrubber is designed to grow its own algae—typically turf or green hair algae—directly on the scrubber’s growth surface. There’s no need to seed it with macroalgae like Chaetomorpha or Caulerpa. The algae will naturally develop as long as your tank has nutrients (nitrates and phosphates), proper flow, and the right lighting.

Q: Do I still need a skimmer with an algae scrubber?

A: Many people will say no. They run lower nutrient tanks and they don't find the need to run both. My answer is going to be yes, skimmers and scrubbers target different forms of waste. While an algae scrubber removes dissolved nutrients like nitrates and phosphates, a skimmer extracts organic particulates before they break down. Together, they create a balanced and efficient filtration system.

Q: Can an algae scrubber run on a nano tank?

A: Absolutely! Upflow algae scrubbers (UAS) are specifically designed for compact setups like nano tanks. Their small footprint and simple installation make them ideal for hobbyists with limited space.

Q: How do I know if my scrubber is working?

A: Healthy algae growth is the best indicator. Look for a vibrant green color and even coverage on the scrubber screen. Brown or slimy algae may indicate issues with lighting, flow, or nutrients that need to be addressed.

Q: Can scrubbers harm coral by removing too many nutrients?

A: Only if the scrubber is oversized or over-harvested. Properly sized scrubbers help maintain stable, low nutrient levels without completely stripping the water. This balance ensures that corals have access to trace nutrients necessary for health and color.

Q: How often should I clean the scrubber?

A: Most algae scrubbers require cleaning every 1–2 weeks. Regular harvesting prevents overgrowth, ensures continued nutrient export, and promotes healthy algae regrowth.

Q: Will using an algae scrubber reduce nuisance algae in my tank?

A: Yes! By outcompeting nuisance algae for nutrients, algae scrubbers can significantly reduce unwanted growth in your display tank. However, proper tank maintenance and water quality are still essential.

Q: What type of algae grows best on a scrubber?

A: Green hair algae and turf algae are the most beneficial types for nutrient export. These grow quickly and efficiently absorb nitrates and phosphates. Slime or cyanobacteria growth indicates the need for adjustments to flow or lighting.

Q: Can an algae scrubber replace other filtration systems?

A: Not entirely. While scrubbers excel at nutrient export, they do not remove particulate matter or provide oxygenation as effectively as protein skimmers. They work best as part of a comprehensive filtration strategy.

Conclusion

Algae scrubbers are the secret weapon your saltwater tank didn’t know it needed. They tackle nitrates and phosphates head-on, keeping your water pristine and your reef thriving—all while harnessing the power of algae, the same stuff you usually curse while scraping your tank walls.

Whether you’re running a nano tank or a reef the size of a small swimming pool, an algae scrubber fits right in, quietly doing its job without demanding endless maintenance or expensive media replacements. Let’s face it: if you’re not using one, you’re probably working harder than you need to. So, why not let the algae work for you?

Happy Reefing... or should I say Happy Scrubbing!