South Seas Flatz 20lb (9kg)
Pack size
20 lb (9 kg) box
Water type
Freshwater + Marine
Part no.
CS0231
South Seas Flatz 20lb (9kg)
Flat rock built for frag plugs, not piled up as a feature boulder. CaribSea South Seas Flatz is a 9 kg (20 lb) box of natural porous calcium carbonate rock, sliced on two sides so every piece offers a genuinely flat surface rather than the odd lucky angle you get searching through a box of raw base rock. Pieces run from roughly 5 cm up to 25 cm or more, in a creamy white natural colour, and the flat faces are what makes this the go-to South Seas product for coral fragging and low-profile ledges rather than bulk structure.
Key features
- Sliced flat on two sides - purpose-built ledges, platforms and shelf faces rather than rock you have to hunt through for a usable flat spot.
- Porous calcium carbonate - the same reef-safe mineral base as CaribSea's other South Seas and Life Rock lines, so it buffers pH and hardness the same way.
- Creamy white base colour - a clean backdrop for coralline growth and coral colour to stand out against once the tank is established.
- Sized for fragging - smaller pieces suit frag plugs and coral propagation setups as well as display aquascaping.
Specifications
| Pack size | 20 lb (9 kg) box |
|---|---|
| Piece size | Approximately 5 to 25+ cm (2 to 10+ in) each |
| Shape | Sliced flat on two sides |
| Colour | Creamy white |
| Material | Natural porous calcium carbonate |
| Biology at purchase | None - dry rock, no bacteria or organisms shipped |
| Effect on water | Buffers pH and carbonate hardness upward |
| Rinsing/soaking | Soak and rinse thoroughly before use, as with other South Seas dry rock |
| Water type | Marine, and freshwater hard-water cichlid tanks |
| Supplier code | CS0231 |
Each piece is a unique natural shape and the product photo is representative rather than exact - the flat faces are consistent, but the surrounding shape of every piece varies.
Which South Seas piece do I need?
| Product | Shape | Best for |
|---|---|---|
| South Seas Flatz | Sliced flat panels, smaller pieces | Frag plugs, thin ledges, low-profile backgrounds |
| South Seas Base Rock | Weathered, porous chunks, 15 to 36 cm | Bulk foundation under the display structure |
| Life Rock Shelf Rock | Flat shelf face, pre-seeded | Finished display shelves that skip the bacterial cure |
Setting it up
Soak each piece in fresh water and rinse thoroughly before it goes in the tank. As dry, uncured rock, plan for a standard cycling period once it is in a marine system before adding livestock - it does not carry the pre-seeded bacteria that CaribSea's Life Rock range does.
Suitable for, and not suitable for
Suitable for: coral frag mounting, low ledges and shelves, sandless substrate beds, and rock footers where a genuinely flat surface matters. Also suits hard-water African cichlid tanks wanting the same calcium carbonate buffering.
Not suitable for: soft-water, planted or blackwater freshwater tanks, where the upward pH and hardness effect works against the setup.
Goes well with
- CaribSea South Seas Base Rock - bulk foundation pieces to build the structure that these flat panels sit on top of.
- CaribSea Seaflor Special Grade Reef Sand - a matching aragonite sand bed for a sandless-look edge against these flat panels.
Warranty and delivery
CaribSea does not publish a warranty term for its rock. Your rights under the Australian Consumer Law apply regardless. The box weighs 9 kg, light enough to combine with a base rock order without pushing the freight total much.
Common questions
What is the difference between Flatz and South Seas Base Rock?
Both are dry porous calcium carbonate rock from the same range, but Flatz is deliberately sliced flat on two sides in smaller pieces for ledges and frag mounting, while Base Rock is larger, unshaped, weathered chunks sold as cheap bulk foundation.
Is this good for fragging corals?
Yes - the flat faces and smaller piece sizes are exactly what frag setups need, whether cut down further for plugs or used as-is for low mounting ledges.
Does it need curing before I add livestock?
Yes. It is dry, uncured rock with no bacteria included, so it needs a soak, a rinse and a standard cycling period in the tank before livestock goes in.
Will it work in my cichlid tank?
Yes, for African Rift Lake or Central American cichlid tanks wanting harder, more alkaline water. It is not the right choice for soft-water or planted freshwater setups.
