Black Seiryu Rock 20kg Box
Water type
Freshwater + Marine
Black Seiryu Rock 20kg Box
A darker take on a classic. Bioscape Black Seiryu Rock brings deep charcoal tones and crisp white veining — the drama of seiryu stone with extra contrast that makes plants and fish colours pop — sold as a 20 kg box of mixed natural pieces.
Key features
- Dark charcoal seiryu-style stone with white veining — the same calcareous mineral rock used in Iwagumi and Japanese-style aquascapes, in a darker colourway.
- High contrast — dark stone makes green plants and bright fish colours stand out more than pale rock.
- 20 kg box of mixed pieces — enough to build a full layout, not one accent stone.
- Hides algae film — dark stone shows green algae film far less than pale rock, a practical bonus that saves scrubbing.
Specifications
| Pack size | Material | Colour | Water type |
|---|---|---|---|
| 20 kg box | Natural seiryu-style stone (calcareous) | Charcoal / black with white veining | Freshwater and marine safe |
Bioscape doesn't publish a piece count or a size range for the box. It's sold and priced by weight, and because it's a natural product the individual piece sizes, shapes and exact colouring inside any given box will vary — we're not printing a size-grading figure that isn't published.
Will it fit my tank?
At 20 kg spread across mixed pieces, this suits scaping a full display tank rather than one accent point. If you only need one or two pieces, the single-piece Black Seiryu Rock listing is the better fit.
Suitable for, and not suitable for
Suitable for freshwater and marine aquascapes, Iwagumi and Japanese-style layouts, terrariums and paludariums, and reptile or frog enclosures. Not a good match for soft, acidic setups — like all seiryu-style stone, it's calcareous and will gradually raise KH, GH and pH as it weathers, which suits hard-water and African cichlid-style tanks better than soft-water biotopes, wild-caught shrimp or plant layouts that depend on low mineral content.
Preparation
Rinse pieces thoroughly before use — washing helps reduce, though doesn't eliminate, the stone's effect on pH. Because the rock is calcareous, bucket-test a piece in a container of your tap or RO water for a few days and check KH, GH and pH before committing it to a soft-water display.
Care and maintenance
No ongoing maintenance once it's in the tank. Expect KH, GH and pH to drift upward gradually over time as the stone weathers; more frequent water changes or an RO/deionised water blend will offset this in setups that need to stay soft.
Warranty and delivery
Covered against being not as described under Australian Consumer Law. As a natural product, piece size, colour and texture vary box to box — the listing photo is representative, not a guarantee of the exact pieces you'll receive. Ships as a 20 kg parcel.
Common questions
Will this raise my water hardness?
Yes, gradually. It's calcareous and slowly releases calcium carbonate, raising KH, GH and pH over time. Wash it well and bucket-test a piece first if you're running a soft-water tank.
How many pieces are in a 20 kg box?
Bioscape doesn't publish a piece count — it's sold by weight, and because every piece is a unique natural shape, the number and size of pieces varies box to box.
What's the difference between this and the regular Bioscape Seiryu Rock?
Colour. Both are the same type of calcareous seiryu-style stone; this is the darker, charcoal-toned variant with white veining rather than the lighter grey stone.
Is it reef safe?
It's aquarium safe for marine systems, but because it's calcareous it will influence water chemistry over time — factor that in if you're dosing to a specific reef target rather than relying on natural buffering.
