Setting up a new aquascape is always exciting, but every aquarist knows about the dreaded “diatom bloom” that often strikes fresh tanks. Diatoms, or brown algae, are one of the most common issues in new aquarium setups. In 2025, with advances in tank technology and water filtration, managing diatoms has become easier—but knowing the best practices is key for a pristine, healthy aquascape.

What Are Diatoms and Why Do They Appear in New Tanks?

Diatoms are microscopic algae that thrive on silicates in water. They often appear as a brown, dusty film on glass, substrate, and decorations in new tanks. Diatom outbreaks are especially common during the initial cycling phase, when nutrient balances are still stabilizing. Understanding why diatoms develop is the first step in preventing them from overtaking your aquascape.

• Silicate-rich substrates and tap water fuel diatom growth
• Low competition from other microorganisms in the tank’s early days
• Uncycled filters unable to process excess nutrients efficiently

2025 Best Practices for Diatom Control in New Aquariums

Thanks to improved aquarium gear and techniques, diatom control in 2025 is more manageable. Follow these expert aquascaping tips to keep your tank clear:

1. Start with RODI or Treated Water

Silicates in tap water are a primary diatom trigger. Use RODI (Reverse Osmosis Deionized) water or a good water conditioner that removes silicates for your initial fills and top-offs.

2. Rinse New Substrates and Hardscape Thoroughly

Sandy or gravel substrates and some rocks can leach silicates. Before adding them to your aquascape, rinse everything thoroughly to minimize initial silicate spikes.

3. Accelerate the Nitrogen Cycle

A cycled aquarium is less prone to diatom blooms. Consider using seeded media from an established tank, bottled beneficial bacteria, or live plants to kick-start the cycling process. For a deeper dive into cycling, check our guide on cycling your aquascape.

4. Limit Lighting in Early Stages

Diatoms thrive on low to moderate light. While your new tank needs some illumination for plant growth, avoid running lights longer than 6–8 hours during the first weeks. Gradually increase intensity as your tank matures.

5. Employ Algae-Eating Livestock

Diatom-eaters like nerite snails, otos (Otocinclus catfish), and shrimp are natural, safe solutions for keeping brown algae under control. Wait until your tank is fully cycled before introducing livestock.

6. Maintain Consistent Water Changes

Weekly water changes (20-30%) help dilute silicates and other nutrients, reducing the resources diatoms need to flourish. This also boosts your overall water quality for thriving aquatic plants.

7. Clean Glass and Hardscape Regularly

Manual removal goes a long way: gently wipe down glass panes and decorations with a clean algae pad or sponge. For stubborn spots, use an aquarium-safe scraper.

Do Diatoms Go Away on Their Own?

Thankfully, diatom blooms are usually temporary. As your tank matures and beneficial bacteria establish themselves, silicate levels drop and diatoms disappear naturally—often within 4–6 weeks. Patience and good maintenance habits pay off!

When Are Diatoms a Sign of a Bigger Problem?

Persistent diatom blooms after the first couple of months might indicate ongoing issues:

• Continuous silicate leaching from substrate or new decor
• Poor water source quality
• Imbalanced lighting or fertilization
• Inadequate filtration or water movement

Consider reviewing your aquascaping setup and water source. Water test kits for silicates can help identify the problem.

Preventing Diatoms in Future Aquascapes

As you gain experience in aquascaping, preventing diatoms becomes second nature. Always use the best available water, rinse materials, and set up a robust filter system for each new tank. Adding fast-growing plants can also help outcompete diatoms for nutrients.

Final Thoughts

Diatoms in a new tank may seem inevitable, but they’re easy to manage with the right aquascaping strategies. By staying proactive with these expert tips, you’ll enjoy a healthy, visually stunning aquarium in 2025 and beyond.

Ready to take your aquascaping skills further? Check our resources on setting up new aquascapes and join our community forum to learn more from fellow enthusiasts!