Before we started building, we ran intensive water-quality tests — measuring pH, ammonia and other indicators — to understand the pond’s condition. The data were clear: ammonia levels were higher than safe limits for fish. Ammonia, which comes from fish waste and decaying organic matter, is toxic even at low concentrations, so action was urgent.

We designed a multi-layered biofilter that borrows from the way natural ponds and wetlands clean water. The core idea was simple: use layers of material to trap solids and create surfaces where beneficial bacteria can thrive and convert ammonia into less harmful compounds. We arranged different sizes of rocks and gravel from largest to smallest, creating pockets where solids settle and bacterial colonies can form. On top of that, we planted aquatic species known for their capacity to uptake ammonia and other nutrients. The system intentionally mimics natural filtration processes — low-tech, low-cost, and sustainable.

Working on the biofilter was not just about construction; it was a study in applied biology and environmental science. We learned why bacterial biofilms are essential for nitrification, how substrate size affects mechanical filtration, and why plant selection matters for nutrient uptake. Creating a biodegradable, eco-friendly system also taught us about lifecycle thinking — choosing materials that won’t harm the pond ecosystem.

The project was a collaborative effort: everyone contributed ideas, from the prototype layout to which local aquatic plants would be most effective. Seeing the filter function for the first time felt rewarding — it confirmed that simple science can produce practical solutions to local environmental problems.