Seachem Gray Coast

Gray Coast™ Calcite is an all natural calcite substrate for all types of marine, reef and tropical aquaria. Its chemical composition will assist in stabilizing calcium and alkalinity while preventing large pH declines. Simply rinse before use to remove any residual dust. Unlike competing “wet” gravels, Gray Coast™ is sold dry: this bag contains 35% more gravel than a bag of wet gravel of equal weight. These “wet” gravels are marketed to give one the impression that they contain living, microscopic animals when in fact they only contain common bacteria. Dry or wet, there are bacteria on every substrate. If one is concerned with shortening the aquarium cycle time for a new system, then the use of a product designed for that particular purpose would be more appropriate (such as Seachem’s Stability®).

• Natural calcite for all types of marine, reef, and tropical aquaria
• Assists in stabilizing calcium and alkalinity
• Helps prevent large pH declines
• High in magnesium
• Maximizes color of marine fish
• Size : 10 Kg

Specifications

What it is. A natural calcite substrate (not aragonite) for marine, reef and tropical aquaria. Seachem’s claim: it helps stabilise calcium and alkalinity and resists large pH declines, the same broad role as their aragonite substrates but from a different mineral base.

Where this sits in the Seachem range. Seachem markets Gray Coast for higher-hardness, higher-salinity setups specifically (marine tanks and African cichlid tanks), noting that magnesian calcite of this type has a higher buffering capacity than aragonite.

Seachem’s own mineral analysis (ppm): calcium 197,500; magnesium 115,400; iron 2,876; manganese 43; strontium 63; vanadium 7; zinc 23; molybdenum 6, notably higher magnesium than either Pearl Beach or Meridian above.

Sold dry, 35% more substrate per bag weight than a wet gravel product, per Seachem.

Pack size. Seachem sells this line in 3.5 kg and 10 kg bags.

Setup & Use

Rinse before use to remove residual dust.

Fill slowly, pouring into a bowl set on the substrate so the bed isn’t disturbed directly, letting water overflow softly onto it.

Initial cloudiness is normal and clears with mechanical filtration or Clarity.

Freshness & Storage

Every batch we dispatch carries a minimum of 6 months’ remaining shelf life. Store this product in a cool, dry place away from direct sunlight, with the cap or inner foil closed tightly after each use.

Filter media and substrates carry no manufacturing or expiry date. Their working life begins on first contact with water, not on the shelf.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number, or email us if you would rather, and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 48 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.