A black substrate of volcanic origin. The granules are 2-5 mm in size and highly porous. Unlike silica sands, the substrate does not compact and contains enough oxygen essential for plant roots and filter bacteria. Plant roots easily grow through the substrate and draw nutrients from the substrate bed. Better water flow also ensures an even distribution of nutrients and temperature throughout the substrate.

Unlike so-called Japanese substrates (dried enriched clays), it does not release excess nutrients into the water. This means extremely frequent water changes (2-3 times a week) are not needed when first setting up the aquarium. Dried clays also tend to bind dissolved substances in the water intensively. This makes things like treating fish and fertilising plants more complicated, as excess fertilisation, mainly with potassium, then becomes necessary.

Chemically neutral, contains only trace amounts of Fe and Mn (mmol/l).
The substrate is porous = it does not compact, and conducts nutrients and oxygen well.
Perfect for rooting and plant growth.
The porous substrate is an ideal home for filter bacteria that clean the water = a healthy, clean environment for fish and plants.
100% natural.
Holds its shape - suitable for creating striking hardscapes.
Does not crumble.
Does not release nutrients into the water - frequent water changes are not necessary.
Easy to handle.

Grain size: 2-5 mm