Beneficial Bacteria & Biofilm

Your filter is not a machine — it is a biological reactor. Inside it live billions of microscopic organisms that are the true engine of your aquarium.

The Bacterial Cast

Nitrifying Bacteria

These are the stars of the nitrogen cycle:

• Nitrosomonas: Converts Ammonia → Nitrite.
• Nitrospira / Nitrobacter: Converts Nitrite → Nitrate.

They live on surfaces with water flow: filter media, sponges, bio-rings, substrate, even plant leaves. They do NOT free-float in the water column.

Heterotrophic Bacteria

The unsung heroes. They break down solid organic waste (fish poop, dead leaves, uneaten food) into dissolved Ammonia, which the nitrifiers then process.

Without heterotrophs, your filter would clog with sludge and the nitrifiers would starve.

Anaerobic Bacteria (Denitrifiers)

Deep inside thick bio-media or deep substrate, where oxygen cannot reach, a third group lives:

• They convert Nitrate → Nitrogen Gas (N₂), which escapes into the atmosphere.
• This is the only biological way to remove Nitrate without water changes.
• Products like Seachem Matrix and Siporax are designed with microscopic pores to create these anaerobic zones.

What is Biofilm?

Biofilm is a slimy, translucent coating that forms on every surface in your tank — glass, wood, rocks, equipment.

It is a community of bacteria, fungi, and microorganisms embedded in a protective polysaccharide matrix (a "slime shield").

Why Biofilm Matters

• Food Source: Shrimp, snails, and fry (baby fish) graze on biofilm as their primary food.
• Surface Colonization: Biofilm is the foundation layer that nitrifying bacteria attach to.
• New Tank Ugliness: The white fuzzy coating on new driftwood is biofilm. It is harmless and will clear up in 1-2 weeks. Do NOT remove it — snails and shrimp will feast on it.

Protecting Your Bacteria

Your bacterial colony is fragile. Here is what kills them:

| Threat | Effect | | :--- | :--- | | Chlorine / Chloramines | Instant death. Always dechlorinate. | | Antibiotics | Can wipe out colonies. Monitor Ammonia after treatment. | | Rinsing filter in tap water | The chlorine in tap water kills bacteria. Always rinse filter media in old tank water. | | Drying out | Bacteria die within hours if the filter is turned off and dries. | | Starvation | If the tank has no Ammonia source (empty tank, no food), colonies shrink within weeks. |

Building Bacterial Colonies Faster

1. Seeded Media: Take a used sponge from an established tank and place it in your new filter. Instant bacteria.
2. Bottled Bacteria: Products like Fritz Turbo Start 700 contain live nitrifying bacteria. Not all brands work — research first.
3. Ammonia Dosing: Feed the bacteria by adding pure ammonia (2-4 ppm) during a fishless cycle.