Seachem Flourite Black 3.5kg
Water type
Freshwater
Seachem Flourite Black 3.5kg
A substrate your plants can actually feed from, not just sit in. Seachem Flourite Black is a stable, porous clay gravel for freshwater planted aquariums. It isn't chemically coated or treated — the clay itself is soft enough that plant roots draw minerals directly from the grains, and because it's a natural mineral substrate rather than a nutrient-dosed one, it doesn't run out or need replacing.
Key features
- Porous clay structure — plant roots extract minerals directly from the substrate rather than relying only on water-column dosing.
- Not chemically coated — won't alter your water's pH.
- Never needs replacing — good for the life of the aquarium, and compatible with undergravel filters without softening or breaking down.
- Use alone or as a base layer under other substrates or hardscape.
Specifications
| Attribute | Detail |
|---|---|
| Weight | 3.5 kg |
| SKU | AA0420 |
| Barcode | 000116372305 |
| Colour | Black |
| Coating | None — uncoated, untreated clay |
| Water type | Freshwater |
Will it fit my tank?
Seachem doesn't publish a fixed coverage figure (litres or kilograms per square metre of tank floor) for this bag size — their own product page instead offers an online calculator that takes your tank's footprint and desired depth. As a starting point for planning, weigh up how many bags you'll need before ordering rather than guessing on one bag for a larger footprint; we're happy to help you work out quantities for your specific tank.
Preparation
- Flourite Black is pre-washed at the factory, but can still be dusty after transit — rinse before use.
- Fill the tank slowly once the substrate is in (the "bowl method" — pour water onto a bowl or plate sitting on the substrate) to avoid disturbing the bed.
- Some initial cloudiness is normal and clears through mechanical filtration, or faster with a water clarifier.
Suitable for, and not suitable for
- Suitable for any freshwater planted aquarium.
- Not chemically coated, so it won't push your pH in any direction.
- Not marketed for marine or reef use — this is a freshwater planted-tank substrate.
Care and maintenance
No replacement needed under normal use. Avoid excessive substrate disturbance once plants are established, and it will continue to work with an undergravel filter without softening or decomposing.
Goes well with
- Seachem Flourish Tabs — root-zone fertiliser tabs pushed into the substrate.
- Seachem Flourish Trace and Seachem Flourish Potassium — water-column dosing to complement root feeding.
Warranty and delivery
Covered by your rights under Australian Consumer Law in addition to any manufacturer guarantee. Ships Australia-wide from North Lakes, QLD.
Common questions
Does it need rinsing before use?
Yes — it's pre-washed at the factory but can pick up dust in transit, so rinse it before adding it to the tank.
Will it change my water's pH?
No, it isn't chemically coated or treated, so it won't push pH in either direction.
How much do I need for my tank?
Seachem doesn't publish a fixed coverage figure for this bag size — contact us with your tank's footprint and desired substrate depth and we'll help you work out how many 3.5 kg bags you need.
Does it need replacing over time?
No — it's a stable mineral substrate, not a nutrient dose, so it's good for the life of the aquarium.
Can I use it with an undergravel filter?
Yes, Seachem states it works fine with undergravel filtration and won't soften or break down.
