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Seachem Flourite Black Sand Review 2024: Pros, Cons & Verdict

Sarah Psaradelis

By Sarah Psaradelis

Customer Rating: 4.5/5
Ease to clean: 4/5
Value for money: 3.8/5
Sheerness: 4/5

If you are looking for a high-quality, durable, and long-lasting substrate for your planted aquarium, then look no further than  Flourite Black Sand. The black color of this clay-based substrate looks striking in an aquascaped and fully planted aquarium. Not only does the rich black color look good, but it can cause the vivid colors of your fish to stand out too.

This porous substrate has a similar appearance to coarse sand but instead is made of inert clay. The size and texture of this substrate are ideal for planted aquariums as it encourages root expansion, which allows the plant to be weighed down by the substrate. However, it does not contain any chemicals or fertilizers that would aid in plant growth.

Seachem is a well-known fish care and maintenance brand, and it develops many professional aquatic products that are affordable and high in quality. It also has a great customer support system if one of its products is not up to standard. Seachem is a United States-based brand that has been in the business for over 40 years and sells a variety of different aquatic-related products.


Seachem Flourite Black Sand – A Quick Look


  • Does not have to be replaced
  • Gives your aquarium a striking look
  • Ideal for planted tanks
  • Good value for money
  • Not coated or treated

  • Must be rinsed before use, or it can turn the water black
  • Does not contain growth-enhancing chemicals


  • Brand name: Seachem
  • Manufacturer: Seachem Laboratories Inc.
  • Item weight: 16 pounds
  • Dimensions: 17 × 11.75 × 1.75 inches
  • Model name: Flourite Black Sand
  • Target: Fish, aquariums
  • Color: Black


Seachem Flourite Black Sand is made from specially fracted porous clay. The substrate itself is lightweight and not sharp. Like most Seachem products, this substrate is of high quality and does not need to be replaced over time, which is a common problem with other types of substrates suitable for planted aquariums. Furthermore, Flourite is a durable and safe material that does not leach chemicals into your aquarium water. The substrate is porous, which allows beneficial bacteria to inhabit the substrate and work alongside your aquarium’s filtration system to keep the water clean, providing your aquarium inhabitants with a safer environment.


Seachem Flourite Black Sand is moderately priced for the amount of substrate you get. However, since this substrate is of higher quality, it will cost slightly more than other brands and types of substrates. The overall amount you need to purchase will depend on the size of your aquarium and the depth of the substrate. It should be noted that purchasing this substrate is typically only a once-off payment. Unlike other types of substrates suitable for planted aquariums, Seachem Flourite Black Sand does not have to be replaced which saves you money.


The best use for Seachem Flourite Black Sand is in planted aquariums. This substrate is great for rooting down plants and giving them a stable and functional growth medium to develop in. Seachem Flourite Black Sand does not leach chemicals into the water, making it safe for the live inhabitants and plants. You can use this substrate with a variety of different fish and invertebrates because it will not alter the pH of your aquarium.

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FAQs: Seachem Flourite Black Sand

Does Seachem Flourite Black Sand Need to Be Rinsed Before Use?

This substrate can be quite dusty, and if it is not rinsed before being added into the aquarium, it could turn the water a murky black color. It’s best to rinse and wash this substrate several times before using it in your aquarium and run the filter for a few days until the murkiness has cleared before adding your fish and plants.

Can You Grow Aquarium Plants in Seachem Flourite Black Sand?

Plants are the main reason this substrate was created. It provides the perfect growth media for plants as it contains a natural source of iron that plants would absorb through their roots in their natural environment. The texture of this substrate is coarse enough to allow plants to develop a proper rooting system.

flourite black sand

What Fish Can Be Kept With Seachem Flourite Black Sand?

Any species of fish can be kept with this type of substrate, including invertebrates such as shrimp and crayfish. The coarse texture is soft enough to not harm bottom feeders who will be scraping along the substrate throughout the day. It will also not alter the aquarium’s water parameters and leach harmful chemicals, so it can safely be used with a wide variety of aquarium inhabitants. The coarse texture will not damage gills if the substrate is ingested, nor will it pose a risk to blocking your fish’s digestive systems if a small amount is ingested.

How Much Seachem Flourite Should You Use in Your Aquarium?

The amount of substrate you use depends on the depth of substrate you need to line the bottom of your aquarium. If you plan to root plants into this substrate, a few inches will be sufficient enough to weigh the plant down before the plant begins to anchor its roots. If you have a large aquarium, you will need to buy the large version of this substrate (15.4 pounds) to have even coverage. If you have a smaller tank below 20 gallons, the 8-pound bag will be enough to give you a thick layer of substrate.

What Benefits Does Flourite Have Over Laurite?

Unlike Laurite, Flourite will not fall apart in the tank and crumble to a muddy consistency—it’s more durable and longer-lasting in comparison. Flourite has the same benefits as Laurite does (providing iron) while providing a place for plants to root themselves, without having to worry about the substrate’s quality deteriorating over time.

What the Users Say

We’ve researched what many different customers had to say about this substrate, and it has all been good things. Most customers claim that this substrate is not as dusty as it seems and that they were able to rinse it several times and place it in their aquarium without having the water turn murky.

Many reviews also stated that this substrate helped their plants grow tremendously and that it’s coarse enough to weigh plants down. The very few negative reviews we found were customers that did not rinse the substrate before putting it in the aquarium and had to deal with the water turning black from the dust. There were few reviews about this substrate harming fish, and more reviews saying that the beneficial bacteria that inhabit this porous substrate helped keep the aquariums parameters stable, in turn keeping fish healthier.

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Seachem Flourite Black Sand is definitely worth purchasing if you are willing to invest in a substrate that will help keep your plants healthy. The contrast of the black sand against a green and natural tank environment is another bonus to this substrate. Not only will your plants flourish and remain healthy, but you will have a substrate that doesn’t need to be replaced and also brings out the color of your fish or shrimp.

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