Here is an important one for anyone who is starting out with their own pond. Aquatic compost is actually very different to normal soil or compost
If you are looking at a bag labeled “Pond Compost” (or Aquatic Potting Compost) in a garden center, it is a very specific tool designed for planting things inside your pond, like Water Lilies, Iris, or Marsh Marigold.
It is fundamentally different from garden compost. In fact, using “normal” garden compost in a pond is a recipe for a green, murky disaster.
Why you can’t use “Normal” Compost
If you put standard potting soil or garden compost into a pond:
- It Floats: Normal compost is full of peat, wood chips, and air. Your plants will float away, and your pond will look like a tea bag.
- Algae Blooms: Normal compost is “leaky.” It releases a massive burst of nitrogen and phosphorus into the water. Instead of feeding your lily, it feeds the algae, turning your water into pea soup overnight.
- Root Rot: In the oxygen-deprived environment at the bottom of a pond, the high organic matter in normal compost can ferment and rot, killing the plant’s roots.
If you buy “Aquatic Compost” at a garden center, it is actually designed for a different purpose: ie it is designed for planting things inside a pond.
- Normal Compost: Is light, fluffy, and full of peat or bark. If you put this in a pond, it floats away and will go on to make the water a murky mess.
- Pond-Specific Aquatic Compost: Is usually a heavy, grit-and-clay-based mixture. It’s designed to stay at the bottom of a pot underwater and release nutrients very slowly so that it doesn’t cause an algae bloom in your pond.
