• Cures underwater or dry — the same 24-hour cure whether the join is submerged or above the waterline, so you can work in the tank without draining it.
• Five minutes of working time — long enough to knead, cut and place a piece properly, short enough that you are not holding a frag for an hour.
• Presses into pore structure — worked firmly around a base or contact point, the putty keys into the rock rather than just sitting on it.
• Two colours, one formula — grey and purple are functionally identical. Seachem lists the choice as aesthetic, so pick the one that disappears into your rockwork.
• Two sizes — 57 g for frag work and single joins, 114 g for larger aquascaping sessions.
• Resealable storage tube — cut off what you need and return the rest to the tube, so a part-used stick keeps.

The useful figure here is not a single cure time but the whole timeline, because what you can do with the putty changes minute by minute after it is kneaded.

1. Wear gloves — latex or nitrile — particularly if your skin is sensitive.
2. Cut off only the amount you need and return the rest to the plastic storage tube straight away.
3. Remove the film and knead the two parts together until the colour is completely uniform. Streaks mean it is not mixed, and unmixed putty does not cure properly.
4. Press firmly around the base or contact point of the coral or rock, working it into the pores rather than smoothing it over the surface.
5. Support the piece for the first fifteen minutes, then leave it undisturbed for twenty-four hours.

Seachem notes that protein skimmers may over-activate during the cure. If your skimmer starts overflowing shortly after you use Seachem Coral Crete, that is the expected behaviour, not a fault — turn it down or off for a few hours and set it back afterwards.

The four options

Every version of Seachem Coral Crete is the same putty. Colour is purely about how visible the join is. Grey blends into dry rock and newly cycled aquascapes; purple blends into established rock that coralline algae has already covered. There is no performance difference between them.

Size is about how much you will use before the tube is opened too often. A frag session of five or six pieces sits comfortably inside 57 g. Building or repairing a structure — arches, overhangs, joining several rocks into one piece — is a 114 g job, and running out mid-build with five minutes of working time on the clock is worse than having some left over.

Suitable for

• Mounting coral frags to plugs, rock and the aquascape
• Joining loose rock into stable structures
• Filling and disguising gaps between rocks
• Repairs made in the tank without draining it
• Work above the waterline, where the same 24-hour cure applies

Not suitable for

• Sealing leaks or bonding glass — that is a silicone job, not an epoxy one. See Seachem Silicone Seal.
• Carrying the load of a large rock structure on its own. Epoxy holds pieces together; it does not replace a properly built, well-supported base.
• Instant bonds. If you need a frag stuck in seconds rather than minutes, Seachem Reef Glue is the right tool.
• Freshwater and planted aquascaping, where Seachem Flourish Epoxy is the matched product.

• Causes skin irritation and serious eye irritation. Wear protective gloves and eye protection.
• Keep the tube tightly closed and away from heat and open flame.
• If it contacts skin, wash with water. If it enters the eyes, rinse cautiously with water for several minutes and seek medical attention if irritation persists.
• Keep out of reach of children.
• Seachem publishes a Safety Data Sheet for this product at sds.seachem.com.

Return unused putty to its plastic tube and seal it. Left in the open, the exposed surface skins over and is wasted. Stored properly, a part-used stick keeps for further sessions.

• Seachem Reef Glue 20 g — cyanoacrylate gel that bonds in seconds underwater, for frags rather than structures
• Seachem Flourish Epoxy 114 g — the freshwater and planted-tank equivalent
• Seachem Silicone Seal 85 g — for glass and sealing work, which epoxy will not do
• Seachem Reef Dip — for treating frags before they are mounted
• Seachem Reef Plus — trace and vitamin supplement for the corals once they are placed

This is a consumable aquarium product, so no manufacturer equipment warranty applies. Your rights under the Australian Consumer Law apply in addition to anything the manufacturer states, including the guarantees that goods are of acceptable quality and fit for the purpose described.

Both sizes ship as ordinary parcels. Store away from heat, and keep the tube sealed in transit and on the shelf.

Does Coral Crete really cure underwater?

Yes. Seachem specifies a 24-hour full cure for Seachem Coral Crete whether the putty is submerged or in air, which is why it can be used inside a running tank without dropping the water level.

Is there any difference between the grey and the purple?

No functional difference. Seachem lists the two colours as an aesthetic choice only — grey blends into fresh dry rock, purple blends into rock already coloured by coralline algae.

Why did the protein skimmer overflow after using it?

Skimmers commonly over-activate while Coral Crete cures. Seachem notes this directly. Turn the skimmer down or off for a few hours and restore the setting once the cure is complete.

How much working time is there once it is mixed?

About five minutes from the point the two parts are kneaded to a uniform colour, then roughly ten more minutes of firming during which only small positioning adjustments are practical.

What happens if it is not mixed thoroughly?

Streaks of unmixed material do not cure correctly, and the join stays soft where they are. Knead until the colour is completely even before placing it.

How should leftover putty be stored?

Cut only what you need and return the remainder to the original plastic tube, sealed and away from heat. That is Seachem's stated storage method and it keeps the unused portion usable.