Biopellets
Biopellets are small, solid pellets made from a biodegradable carbon source, used inside a dedicated reactor to help lower elevated nitrate and phosphate levels in a reef aquarium. They work by feeding a specific type of bacteria that consumes both the carbon in the pellets and dissolved nutrients from the water, converting them into bacterial biomass that can then be physically removed from the system.
Biopellets have become a popular tool for hobbyists running nutrient-dense systems who want a continuous, low-maintenance method of nutrient export beyond water changes alone.
Why It’s Important
- Helps reduce elevated nitrate and phosphate levels in tanks struggling with excess nutrients.
- Supports ultra low nutrient system approaches that some SPS-focused reef keepers pursue.
- Reduces reliance on frequent, large water changes as the primary method of nutrient control.
- Runs continuously in a dedicated reactor, requiring only periodic maintenance rather than daily attention.
How It Works
Biopellets are placed in a reactor where water flow gently tumbles them, slowly eroding their surface over time. Bacteria colonize this surface and consume the dissolved carbon it provides as an energy source, and in the process, they also draw in ambient nitrate and phosphate from the water to build new bacterial biomass.
As this bacterial biomass grows and sloughs off the pellets, it needs to be physically removed from the system, typically by a protein skimmer, which is what actually exports the nitrate and phosphate that the bacteria have converted into biomass.
Flow rate through the reactor also matters more than it might seem. Too little flow can leave pellets clumped together with reduced surface contact, slowing bacterial colonization, while too much flow can tumble pellets so aggressively that they wear down faster than intended. Most reactors are designed with a recommended flow range specifically to keep pellets gently suspended and evenly exposed to water flow.
Biopellets and Related Methods
Biopellets are closely related to carbon dosing, since both methods work by feeding bacteria a carbon source to drive nutrient consumption. They’re directly tied to nitrate and phosphate levels, to protein skimmers, which are essential for actually removing the resulting bacterial biomass, and to broader nutrient export strategies used in ultra low nutrient systems.
Common Misconception
A common misconception is that biopellets start reducing nutrients immediately after being added. In reality, the bacterial colony needs time, often several weeks, to establish itself on the pellet surface before nutrient reduction becomes noticeable. It’s also a mistake to run biopellets without a properly functioning skimmer, since without a way to export the bacterial biomass produced, the nutrients simply cycle within the system rather than actually leaving it.
The Bottom Line
Biopellets are a carbon-based nutrient export method that fuels bacteria to consume excess nitrate and phosphate, which are then removed from the system through skimming. Used correctly, and paired with a capable skimmer, they offer a steady, low-maintenance way to keep nutrients in check over the long term.
