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Seachem Flourite Black Clay Gravel – Stable Porous Natural Planted Aquarium Substrate 15.4 lbs



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  • GRAVEL: Seachem Flourite Black is a specially fracted stable porous clay gravel for the natural planted aquarium. Its appearance is best suited to planted aquaria, but may be used in any freshwater aquarium environment.
  • AQUARIUM BED: Gravel modifiers such as laterite are not necessary when using Seachem Flourite Black as this product is most effective when used alone as an integral substrate bed, but it may be mixed with other gravels.
  • SET-UP: When adding water to the aquarium, fill slowly to avoid disturbing Flourite Black substrate bed. Place a bowl in the aquarium and add water directly to the bowl, allowing water to overflow softly on to the gravel bed. Initial cloudiness is normal, but to remove this simply use mechanical filtration
  • COMPATIBLE: Flourite Black substrates will work fine with an under gravel filter and will not soften or decompose to an unsuitable state within your tank.Flourite substrates will work fine with an UGF
  • SAFETY: Seachem Flourite Black is not chemically coated or treated, thus does not alter the pH of the water. Flourite Black is beneficial for the life of the aquarium and need not be replaced.

Specification: Seachem Flourite Black Clay Gravel – Stable Porous Natural Planted Aquarium Substrate 15.4 lbs

Item Weight

15.4 Pounds




Seachem Laboratories, Inc.

Item model number


Date First Available

May 15, 2008

Item Package Dimensions L x W x H

16.65 x 9.37 x 5.12 inches

Item Dimensions LxWxH

17 x 11.75 x 1.75 inches

Brand Name


Target Audience Keyword

algae-eaters, mollusks, octopuses, snails, fish, Fish, rays

Model Name

Flourite Black 7kg




15.4 lbs



Age Range Description

All Life Stages

Number of Items




Specific Uses for Product


5 reviews for Seachem Flourite Black Clay Gravel – Stable Porous Natural Planted Aquarium Substrate 15.4 lbs

4.8 out of 5
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  1. dreamer_rt

    After reading reviews and researching this product for weeks, it became clear to me that the single most important thing was not rinsing the living crap out of it, but to cure it under the sun. So I did exactly that, spending less than 15 minutes total rising my three bags and ending up with a fabulous, cloud free tank.

    I filled a 5 gallon bucket halfway and poured one of the bags into it. You can see from the photos that the resulting goo is not something you would EVER under ANY circumstance add to an exiting tank, or a new one for that matter! I poured that mess of a clay soup out and refilled the bucket halfway. I did that about 5 more times until the water was 90% clear. I repeated that process twice more for the other two bags then spread the Flourite out on a fitted sheet.

    I must point out here that had I wanted, I could have easily kept rinsing until the gravel was crystal clear, but I did not.

    Anyway, after about three hours under the sun, I emptied it into two buckets. The Flourite was bone dry and had a million tiny particles in it so it was a bit dusty. I poured about a gallon of water into each pail to keep the dust down then added it to the tank. I then filled it five gallons at a time, pouring the water onto one of the rocks in my tank. I immediately added my plants and despite all the rustling of the gravel to get them rooted, there was no cloud. Yay!

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  2. Green girl 87

    I only do low tech planted tanks, I mix this with black gravel to save $$, but it does seem to help with plant growth, with help from liquid fertilizer. Looks good, maintains dark black color. Don’t need much rinsing. I put this in all my tanks now.

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  3. Pepperberryinn

    Good clay gravel-like substrate. Black looks good in my tank. Rinsed and soaked for a week, multiple rinses per day in bathtub with strainer. Natural looking. Live aquarium plants doing well. Fish doing great. Rinse it diligently and you an your fish will be happy. Get the big bag!

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  4. Richard

    Wow does this stuff look good. It’s definitely not the cheapest inert substrate out there, and WOW is it dirty when it comes in the bag, but its definitely the nicest inert substrate I know of.

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  5. dreamer_rt

    So when I first decided to get some of seachem’s flourite for my aquarium, I accidentally got the regular red/brown color instead of black. The bag had busted open in the box, so I was able to see what it looked like before returning. The flourite black is much finer particle size than regular. And quite finer that standard aquarium gravel. Idk how this will affect it being in the aquarium as substrate, but it did make it a pain to clean.

    So the directions on the bag suggest you rinse it. I would say rinsing it is a requirement. And because it is so fine, you’ll need a fine mesh strainer for this. Get yourself 2 buckets. Dump all your gravel in one. Use a strainer to rinse it in the sink and then dump the clean gravel in the other bucket. Time consuming? Yes. But the water that came out of the gravel when I did this was a murky grey/black color. I definitely would not want this in my aquarium. I don’t even want to imagine how many gravel vacs and water changes it would take to get out.

    Here is the detailed way I strained it. Once the water comes out clear from rinsing, I would shake/sift it around in the strainer. I discovered that a mess of tiny particles come out in the sink, see pics. So I would tip the strainer enough that I could use my hand and the water to get all those tiny particles off the bottom of the strainer. Be careful to not tip so much that your relatively larger sized gravel particles fall out of the top of the strainer. Then I sifted again and did this rinsing of the bottom of the strainer again. Like I said, it was time consuming. Also, if you don’t want some of these super tiny particles going down your drain, I suggest getting a fine mesh sink strainer. I know my sink is already a little slow draining and needs the trap underneath cleaned out. So I wasn’t terribly concerned about it.

    As far as quantity, I ordered three 15.4 lb bags. The first pic is how they look in a 55 gallon tank. I haven’t properly leveled it out yet, but it is approximately 2 inches total, with 1 inch being visible above the frame. I would actually like just a little more than this. But my plan is to mix some regular aquarium gravel in with it for a pop of color. Though this level of gravel is fine for this tank. It is just a personal preference. And I almost just ordered 2 bags, but I don’t think that would have been enough.

    Once I do add my colored gravel in and get it set up and going with my plants, I will update this review.

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    Seachem Flourite Black Clay Gravel – Stable Porous Natural Planted Aquarium Substrate 15.4 lbs
    Seachem Flourite Black Clay Gravel – Stable Porous Natural Planted Aquarium Substrate 15.4 lbs


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