Phosphates ($PO_4$) and Silicates ($SiO_2$)

Nitrate isn't the only nutrient in town. To master algae control, you must understand the secondary nutrients.

Phosphates ($PO_4$)

Sources:

1. Fish Food: Most flake/pellet foods are rich in phosphorus (it's a preservative and vital nutrient).
2. Tap Water: Agricultural runoff often puts phosphates in city water.
3. pH Buffers: Many "pH Up" or "pH Down" products are phosphate-based.

The Balance:

• Too Low (< 0.1 ppm): Plants get "Green Spot Algae" on older leaves. Growth stops.
• Too High (> 2.0 ppm): If Nitrates are low but Phosphates are high $\rightarrow$ Blue-Green Algae (Cyanobacteria) explosion.

Target: Keep Phosphates around 0.5 - 1.0 ppm in a planted tank.

Silicates ($SiO_2$)

Silicates are the primary building block for Diatoms (Brown Algae). Diatoms have silica shells (glass houses). Without silicates, they cannot reproduce.

Sources:

1. New Sand: Playground sand or blasting sand often leaches silicates for the first few months.
2. Tap Water: Often high in silicates.

The Cycle: New tanks almost ALWAYS get a Brown Algae bloom at month 1. This is because the silicates in the water/sand are high. Once the diatoms consume all the silicates, they starve and disappear naturally. Do not panic. It is a self-correcting problem.

Controlling Nutrients

1. Water Changes: Resets the levels.
2. PhosGuard / GFO: Chemical media that absorbs Phosphates and Silicates. Use if your tap water is the source.
3. Feeding: Rinse frozen food (the juice is pure phosphate!).