A bag of gravel sold as "natural" is really promising variation rather than uniformity, and that's the point rather than a flaw - a manufactured, identical grain in every bag would be a different, coated product.

This is a Harlequin colour blend of natural aquarium gravel, suitable for coldwater, tropical and saltwater set-ups alike. It works as a planting substrate too, with an enhanced surface area, and it's described as maintaining pH stability rather than shifting it.

• Natural aquarium gravel, sold as a 2kg bag
• Colour and size vary bag to bag, as it's a natural product
• Suitable for coldwater, tropical and saltwater set-ups
• Works as a planting substrate with enhanced surface area
• Maintains pH stability rather than altering it

On consistency. Because it's a natural product, expect the exact mix of colours and stone sizes in your bag to differ slightly from the next one - Pettex don't publish a fixed grain size, so if matching existing gravel in an established tank matters to you, order more than you think you need in one go rather than buying again later.

Who it's for: fishkeepers setting up or topping up a coldwater, tropical or saltwater tank who want a natural-look gravel that also works as a planting substrate.