Getting rid of brown algae, commonly known as diatoms, in a reef tank involves a combination of physical removal and addressing the underlying nutrient issues that cause them.
Brown algae are typically diatoms, a type of single-celled organism that forms brown layers on sand, rocks, glass, and equipment. They often appear in new tanks or when nutrient levels, particularly silicates and phosphates, are elevated.
Here are key strategies to combat brown algae:
1. Physical Removal
Physically removing the algae prevents it from spreading and makes it easier for filtration systems to handle.
- Vacuum the Substrate: Use a gravel vacuum to hoover the sand bed. This is crucial as brown algae often thrives there. Once you've collected the algae and debris, it's important to discard and replace the dirty water that was siphoned out to remove the nutrients and silicates trapped within it.
- Scrape Surfaces: Gently scrape brown algae off the glass, rockwork, and equipment using an algae scraper or brush suitable for your tank material (e.g., plastic or acrylic-safe scraper for acrylic tanks).
- Clean Equipment: Regularly clean pumps, heaters, and other equipment where algae can accumulate.
2. Mechanical Filtration
Using mechanical filtration is essential to capture the free-floating algae particles and debris dislodged during physical cleaning.
- Filter Socks, Filter Wool, or Clarisea: As the reference states, Mechanical filtration like filter wool, filter socks or a Clarisea will physically catch some of the brown mess and you then remove it. These filter media trap particles from the water column. Ensure you clean or replace filter socks and filter wool regularly (daily or every few days when dealing with a bloom) to export the trapped nutrients from the system. A Clarisea performs this process automatically by rolling up the dirty filter fleece.
3. Address Nutrient Sources
Diatoms bloom when excess nutrients, especially silicates and phosphates, are available. Identifying and controlling these sources is vital for long-term eradication.
- Use High-Quality RODI Water: Tap water often contains silicates and other impurities. Always use purified Reverse Osmosis De-Ionized (RODI) water for top-offs and water changes. Ensure your RODI filter system is functioning correctly and its filters/resin are not exhausted.
- Perform Water Changes: Regular water changes with clean RODI saltwater help reduce overall nutrient levels in the tank water.
- Improve Water Flow: Ensure adequate flow throughout the tank to prevent dead spots where detritus and nutrients can settle, fueling algae growth.
- Control Feeding: Avoid overfeeding your fish and invertebrates. Uneaten food breaks down and adds nutrients to the water.
- Check Source Rock/Sand: Some rock or sand types can leach silicates, especially in a new tank. Ensure your dry rock or sand is properly rinsed or cured.
- Utilize Nutrient Export Methods:
- Protein Skimmer: A good protein skimmer effectively removes organic waste before it breaks down into nitrates and phosphates.
- Refugium: Growing macroalgae in a refugium consumes nitrates and phosphates, outcompeting nuisance algae.
- Chemical Filtration: Using phosphate or silicate-removing media (like GFO or specific silicate removers) in a media reactor or filter bag can help lower their levels.
4. Introduce a Clean-up Crew
Some invertebrates naturally graze on diatoms.
- Snails: Various types of snails, such as Trochus, Nerite, and Cerith snails, are known to consume diatoms.
- Hermit Crabs: Some hermit crab species will also pick at diatoms on sand and rock.
Summary of Methods
Here’s a quick look at the key strategies:
| Method | Description | Primary Benefit | Related Reference Detail |
|---|---|---|---|
| Physical Removal | Scraping glass, vacuuming sand/rocks. | Immediate visual improvement | Gravel vacuum to hoover the sand bed, discard and replace the dirty water. |
| Mechanical Filtration | Using filter socks, wool, or roller filters to trap particles. | Removes suspended algae/debris | Mechanical filtration like filter wool, filter socks or a Clarisea will physically catch some of the brown mess and you then remove it. |
| Nutrient Control | Using RODI water, water changes, protein skimming, refugiums, chemical media. | Addresses root cause (nutrients) | Indirectly supported by the need to remove "dirty water" from vacuuming. |
| Cleanup Crew | Adding snails or hermit crabs that eat diatoms. | Natural grazing/maintenance | N/A (not mentioned in the provided reference). |
Successfully getting rid of brown algae requires persistence, combining consistent physical removal with diligent control of nutrient inputs and effective nutrient export.
