Seachem Flourite Black, 7 kg / 15.4 lbs

Seachem Flourite Black is a specially fracted, stable, porous clay gravel for natural planted aquariums. This is the 7 kg / 15.4 lbs bag. It can be used in any freshwater tank, but its look and structure are aimed at planted setups. It is a gravel, distinct from Seachem’s finer Flourite Black Sand.

Use it alone

Seachem says gravel modifiers such as laterite are not necessary, because Flourite Black works best used alone as an integral substrate bed. You can still mix it with other gravels if you want to change the look or stretch a bag.

Does not change pH

It is not chemically coated or treated, so it does not alter water pH. That separates it from active soils, which lower pH and soften water. Flourite Black suits tanks where you want stable chemistry, including harder water livebearers.

Long life

Seachem says it will not soften or decompose and need not be replaced. Unlike soils, it will not break down into mud over the years. It even works with an under gravel filter.

Setup

Seachem’s advice for filling: place a bowl in the aquarium and add water directly into the bowl, so it overflows gently onto the gravel. Initial cloudiness is normal; mechanical filtration clears it. A light rinse first helps too.

Nutrients

Clay gravel holds nutrients from the water column well, but it is not a rich soil. Feed root plants with tabs like Seachem Flourish Tabs, especially swords and crypts.

How much

A 15.4 lbs bag gives a 2 inch bed in a small to mid-size tank. For 20 gallons and up, plan on two bags.

Who it suits

Low-tech and mid-tech planted tanks where the keeper wants a substrate to last for years without fuss or chemistry changes.

The dark color sets off green plants and bright fish nicely, and it hides mulm better than light sand.