Kruger Meier Onyx Magma Stones 4-8 mm - Aquarium gravel 2kg

It's not just a substrate – it's an active foundation that significantly impacts life in the tank. Onyx Magma Stones are porous, natural lava that acts as a biological filter. With each grain, it supports the development of beneficial bacteria, absorbs impurities, and helps maintain stable, clean water.

You can use it as a bottom layer under sand or gravel, but also as a standalone, main substrate. Its dark, raw texture is perfect for biotope tanks, natural arrangements, or hardscape. It creates a beautiful contrast and adds depth to the entire composition.

Onyx Magma Stone is a porous volcanic rock that acts as a quiet hero of the substrate. You place it at the bottom, under gravel or sand. That's where the magic begins:
- absorption of impurities,
- growth of good bacteria,
- natural improvement of water quality.

It's up to you to decide what role it will play – technical or aesthetic. Either way, it does a great job.

Why is it worth choosing?
- Natural magma rock – no additives, no chemicals
- Porous structure – ideal for nitrifying bacteria
- Biological filtration at the base
- Helps maintain clean and healthy water
- Can be a base for other substrates or a standalone material
- Raw appearance – fits natural, low-tech tanks and biotopes

Pro tip:
Before use, rinse the stone – it may contain dust from transport. Lay it as a technical layer or leave it on top – it looks great and works well. Naturally.