Onyx Magma Stones 4–8 mm – Aquarium gravel, 2 kg
Porous volcanic lava substrate with 4-8 mm grain, sold in 2 kg packs. Suited to aquarists who want a dark…
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Find a productProduct description
Onyx Magma Stones 4-8 mm is a porous volcanic rock sold as an aquarium substrate. It is intended for aquarists setting up biotope, natural or low-tech tanks who want a dark, raw base layer. It can serve as a technical underlayer beneath sand or fine gravel, or be used alone as the main substrate.
Why it matters
- Porous structure: the supplier describes the rock as porous volcanic lava, a surface on which nitrifying bacteria can establish in the substrate.
- Biological filtration in the base layer: placed under a top layer, the rock works in the bottom of the tank, where the supplier states it supports beneficial bacteria and helps absorb waste.
- Dual use: it can be buried as a technical layer or left exposed on the surface, where it serves as a decorative element.
- Natural, untreated material: the supplier states it is magmatic rock with no additives. Rinse before use, as it may contain dust from transport.
Specifications
- Grain size: 4-8 mm
- Weight: 2 kg
- Material: volcanic (magma) stone
- Brand: Kruger Meier
- Symbol: KM ONYX MAGMA STONES 4-8
- EAN: 5907059402098
- Category: Exotic aquatics > Substrates, decorations, rocks and plants > Substrates
What it works with
This substrate fits freshwater aquariums that call for a dark, rough texture, including biotope, natural and hardscape layouts. Because the stone is rough and porous, it pairs well with a finer top layer of sand or gravel, which then covers the rock. The listing does not specify tank dimensions or compatible species, so check those requirements against your setup.
Technical specification
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Frequently asked questions
Yes, the supplier recommends rinsing it first, because it may contain dust left over from transport. Rinse it before adding it to the aquarium.
Both options are possible. You can place it on the bottom as a layer under sand or gravel, or use it as the main substrate on its own.
The grains are 4–8 mm, as stated in the product name. The dark, rough texture suits biotope, natural and hardscape layouts.
The supplier describes it as natural volcanic (magmatic) rock with no additives. Its porous structure is intended to give bacteria surface area to colonize.
One pack contains 2 kg and costs 13.99 zł gross.
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