Seachem Gray Coast 3.5kg

I switched to this substrate because I wanted something that would help buffer the water chemistry without using additives, and it's noticeably improved my reef tank's stability. The calcite composition really does seem to keep calcium and alkalinity levels more consistent between water changes.

The grain size is consistent across the whole bag, making it easy to spread evenly in the tank. My water parameters stabilized faster than with my previous substrate, and the calcite really does seem to help with alkalinity. It’s a solid choice for a natural-looking freshwater setup.

I was a little worried about cloudiness, but after a gentle rinse and filling the tank, the water was clear within a few hours. My corals look noticeably more vibrant, and I love that the grains are uniform enough for my goby to sift through easily. A solid choice for a stable reef setup.