Aquarium sand: what the different types are for
Aquarium sand comes in a few distinct types — fine silica sand, coarser natural sand, and coloured or coated decorative sand — and the right one depends more on what fish or plants you are keeping and how the tank is filtered than on which one looks best in the shop. Getting the grain size and preparation right matters more than the colour.
Fine sand vs coarser grades
Very fine sand suits fish that naturally sift through soft substrate, since a coarser gravel can be uncomfortable or impossible for them to dig through the way they would in the wild. It also gives a smoother, more natural-looking base for a planted or aquascaped tank.
The trade-off is that very fine sand compacts more easily than gravel, which can trap pockets of trapped gas underneath if it is not disturbed occasionally. A coarser sand or fine gravel mix is more forgiving for a tank without dedicated bottom-dwelling fish, and easier to keep clean with a standard gravel vacuum.
Coloured and coated sand
Coloured aquarium sand is usually a natural sand with a coating applied to change its appearance, and reputable aquarium-specific products are made to be inert and safe once rinsed, unlike sand intended for other uses such as building or play sand, which should never go in a tank.
If you want a specific look rather than a natural sandy colour, choosing a product made and sold specifically for aquarium use is the safer route, since it is tested for fish safety in a way a general-purpose sand is not.
Preparing and adding sand to a tank
Rinse any new sand thoroughly before it goes in the tank, regardless of type, until the water runs mostly clear rather than cloudy. Skipping this step is the single most common reason a newly set-up tank stays murky for days.
Add sand to an empty or newly set-up tank rather than pouring it into an established one with fish already in, since disturbing an existing substrate releases trapped debris and can cloud the water and stress the fish already living there.
Choosing what suits your tank
For a general community tank without bottom-dwelling species, a fine gravel or coarser sand is usually the easier option to maintain. For fish that specifically sift or burrow, a genuinely fine, aquarium-rated sand is worth the slightly higher maintenance.
Whatever you choose, match the substrate depth to what your filter and any plants need, and avoid mixing substrate types unevenly across the tank, which can create patches that behave very differently when it comes to cleaning and gas exchange.
What we stock
Everything below is in stock with us, priced with delivery worked out, and packed and posted by hand in the UK.
Large Aquarium Maintenance Set
A 48-inch condensation tray, a 22-inch glass scraper, a digital thermometer and 250ml of AquaSafe for a big tank.
£32.49
Supa Aquarium Net
Supa aquarium nets in coarse and fine meshes for fish catching and tank maintenance
From£1.65
Marina Digital Aquarium Thermometer
A digital aquarium thermometer that mounts on the outside of the glass and reads easily
£3.49
Marina Deluxe Aquarium Scraper
A four-in-one aquarium tool: two pad faces, a scraper blade and a planter fork
£8.79
Marina Floating Aquarium Thermometer
A floating aquarium thermometer with a safe-zone marker for tropical fish
£3.49
Supa Condensation Tray
A 48-inch aquarium condensation tray, shielding the hood's electrics from tank water
£11.49
Aquatic Roman Gravel Jet Black
2kg jet black aquarium gravel, inert and colourfast for coldwater, tropical or marine tanks
£3.99
Pettex Aquatic Roman Gravel Natural Lakeland
Natural Lakeland-tone aquarium gravel for coldwater, tropical or saltwater tanks
From£3.99
Pettex Aquatic Roman Gravel Blend Mix
Natural blended-colour aquarium gravel for coldwater, tropical and saltwater tanks
From£3.99
Roman Gravel Jet Black
8kg of natural jet black aquarium gravel for coldwater, tropical and saltwater set-ups
£12.49
Rosewood Pet Keeper Plastic Tank Medium
7.2L ventilated plastic holding tank for small pets and fish, 30 x 30 x 20cm
£13.49
Common questions
- Do I need to rinse aquarium sand before using it?
- Yes, always rinse new sand thoroughly before adding it to a tank, regardless of the type, until the water runs mostly clear. Skipping this is the most common reason a newly set-up tank stays cloudy for days afterwards.
- Can I use playground or building sand in my aquarium?
- No, stick to sand made and sold specifically for aquarium use. General-purpose sand is not tested for fish safety and can contain additives or a chemical composition that is not suitable for an aquarium environment.
- Is sand or gravel better for a fish tank?
- It depends on what you are keeping. Fine sand suits fish that naturally sift or burrow through soft substrate, while gravel is often easier to maintain and better suited to a general community tank without bottom-dwelling species.
- Can I add sand to a tank that already has fish in it?
- It is better to avoid it where possible, since disturbing an established tank to add substrate can cloud the water and stress the fish already living there. Adding substrate before a tank is stocked is the more straightforward approach.
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Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.