Onyx Sand - 15.4 lb.

SKU: 198742
Manufacturer: Seachem
MPN: 3505

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Are you looking for a unique way to make your aquarium really stand out? Onyx Sand is a great way to make a statement Pitch-black, sparkling sand, completely safe for fresh and salt water. This sand does have a slight buffering capacity, as well. All natural, no artificial coatings. Ideally suited to planted aquaria and most effective when used alone.

The size and color of the gravel and substrates listed can vary due to natural availability and the resolution of your computer monitor.

For help selecting how much gravel you need for your aquarium, check our Aquarium Substrate Buying Guide.


Package Size15.4 lb.
Internal Id


Although pre-washed, it may be rinsed before use to remove residual dust. Dust can also be minimized by filling aquarium slowly and dispersing water so that the Flourite bed is not disturbed. Slight initial cloudiness is normal and will clear rapidly (2–12 hours). To shorten the cloudiness period use Seachem Clarity in conjuction with mechanical filtration (such as filter floss).

Ratings & Reviews

2 reviews

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Great Product


I mixed the Onyx sand with the Onyx gravel and it provided an excellent consistency for my 29 gallon starter cichlid aquarium. It looks awesome and I'm very happy with the result. Both the Onyx sand and gravel will require a thorough rinsing but it's worth it. Another great product from Seachem.

Do Not Buy!


Had to rinse this like 20 times and my aquarium water is still cloudy. For the first couple of rinses, it looked like there was cement in the bucket I was using to rinse it. Once in the aquarium and stirred up, one of my brand-new filters broke. I got another one and the exact same thing happened when the sand was moved on the bottom. At this point, I honestly don't know what to do.

Mine also is not black in the aquarium, more like a very light gray. It's in there no

This is no reflection on That Fish Place because 2 of the 4 bags I purchased were from another retailer.

In my opinion this stuff is just expensive garbage!