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Best Fish Tank Substrates for 2020

With very few exceptions, all fish tanks need some sort of material on the bottom. This can generally be either gravel or sand, but other materials are also available depending on the conditions your fish need to live in and whether you have a planted tank.

Because it shouldn’t be changed or altered when your fish are in their tank, it is vital to get it just right when initially setting up your aquarium.

We have included the best pick for all types of fish tank substrate below, ensuring they are safe for your fish, popular picks and great value.

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    Our Top Picks

    Image Product Details
    Pets At Home Natural Mix Aquarium Gravel
    • Made from silicate aggregates
    • Can be used in any water
    Check Price
    Marina Decorative Aquarium Rainbow Gravel
    • Good medium size
    • Epoxy-coated to encourage good bacteria
    Check Price
    Roman Gravel Sand
    • Choice of colours
    • Good for planting
    Check Price

    Top 10 Best Fish Gravels and Sands Reviewed

    1.
    Pets At Home Natural Mix Aquarium Gravel

    A great mix of different colours, gravel sizes and silicate types for your tank to really have that natural sea feel and keep all of your fish happy.

    It looks decorative but also gives your fish somewhere perfect to explore and play in. the stones will need rinsing thoroughly before they are placed in your tank, but the colourfast resin coating will ensure that the colour doesn’t start leaking into your water over time. This also means it won’t affect the pH levels or cloudiness.

    If you have plants, it makes a perfect medium due to the smaller size, allowing good bacteria to grow and the plant to remain in place. You can purchase it in a 2kg or 8kg bag, so you get the perfect amount for your tank size.

    Features

    • Made from silicate aggregates
    • Can be used in any water

    Specifications

    • Colours: Natural Mix
    • Bag Size: 2kg/8kg
    • Tank Type: Any

    2.
    Marina Decorative Aquarium Rainbow Gravel

    Hugely colourful gravel can really help when your fish are also hugely colourful, such as a school of Tetras.

    With the contrast of the green plants and decorations, it will make a striking display. This Marina collection is dust-free, non-toxic and epoxy-coated, making it perfect for use in an aquarium. It is the ideal size to provide a perfect breeding ground for bacteria colonisation, to maintain clear water.

    As with all gravel, wash before you use to remove any dust. Users have said that the colour still remains as vivid one or two years on, which is great news for longevity.

    Features

    • Good medium size
    • Epoxy-coated to encourage good bacteria

    Specifications

    • Colours: Rainbow
    • Bag Size: 450g, 2kg
    • Tank Type: Any

    3.
    Roman Gravel Sand

    Sand is great for burrowing fish or those bottom-feeders, or indeed as a base under your gravel to keep plants and other decorations secure.

    Available in four colour varieties, you can pick the one which will make your tank look just the part. It is great to use as a plater medium due to the fine size, and it all looks really dazzling under lighting.

    Sand needs turning to aerate it every so often, but this one is easy to clean with a vacuum held far enough away as any dirt just sits on the top layer. It is great for axolotls or bottom-dwelling fish as it is soft and easy to walk on or burrow into.

    Features

    • Choice of colours
    • Good for planting

    Specifications

    • Colours: Black, Pewter, Quartz, Speckled
    • Bag Size: 8kg
    • Tank Type: Any

    4.
    BiOrb White Feng Shui Marble Aquarium Pebbles

    Pebbles are best used as decorative elements or to secure your ornaments and plants if you have fish who like to pull and play with them, moving or bringing them out.

    They are all large stones, so won’t easily be disturbed by small fish. They’re ordinary smooth stones, so will need taking out and cleaning occasionally, but once they have been washed they are safe for use in your tank.

    How many you get in a bag differs, unfortunately, but in general, it seems to be between 8 and 12 large stones to make up the overall weight which should be enough for decorative issues. If you’re thinking that they’re expensive so you should nip to the beach and pick some up instead, think again – these ones are the safest and least toxic for your tank water.

    These are also ideal for using in a dedicated small BiOrb with just one or two fish in.

    Features

    • Large
    • Great as decoration or security

    Specifications

    • Colours: White, Black, Green, Red
    • Bag Size: 912g
    • Tank Type: Any

    5.
    Fluval Stratum Volcanic Soil

    If you have a planted tank and living plants which require just as much care and attention as the actual fish, getting the best layer of any substrate to help them stay alive is vital.

    This volcanic soil, which looks like little balls, stimulates strong plant growth, making it better than using sand or stone. It helps keep the tank at a neutral to slightly acidic pH level, so is best for tanks where the fish require this level.

    The plant roots easily branch into the substrate, spreading as they grow and becoming more secure for any fish who are a bit mischievous and like to pull at them. If you have shrimp it can also be great, as they can hide in the substrate until they are old enough to come out and not be bullied or threatened.

    It’s not good for any fish who like to move the tank bedding around, nor African and Central American cichlid species, goldfish or koi. It also can’t be used in saltwater, and shouldn’t really be used with other gravel mixes.

    Features

    • Lightweight and porous

    Specifications

    • Colours: Black
    • Bag Size: 2kg, 4kg, 8kg
    • Tank Type: Plant, Shrimp, Tropical

    6.
    GardenersDream Coloured Aquatic Gravel

    One of the best for overall choice, in terms of both colour and bag sizes, so you can find the perfect match for your tank.

    It is not toxic and remains dust-free once initially rinsed. Each piece is between 3mm – 8mm, so it is good for little fish who like to burrow and hide as well as larger ones who may want to move things around.

    Great quality, don’t be put off by the fact it can also be used as a plant pot topper. If you have some leftover, at least this means it will still come in use!

    Features

    • Colour choice
    • Good quality and low dust

    Specifications

    • Colours: Black, White, Green, Orange, Yellow, Blue, Purple, Red, Rainbow
    • Bag Size: 1kg, 2.5kg, 5kg, 10kg, 20kg
    • Tank Type: Any

    7.
    Aquatic Roman Gravel Natural Cream

    A choice of ten neutral finishes and colours means you can pick the exact look you’re after for your fish tank.

    It is suitable for cold water, tropical and saltwater tanks, and the small size means there is a higher surface area which makes it ideal for anaerobic activity and good bacteria production. It also makes for the perfect planting medium.

    Suitable for bottom feeders and barbed fish as the edges aren’t too harsh and sharp. As they’re made from silica aggregates, they’re pretty inert and they’re covered in colourfast resin to ensure there is no pollution in the tank.

    Features

    • Colour choice
    • Good for all tanks and fish

    Specifications

    • Colours: Choice of 10
    • Bag Size: 8kg
    • Tank Type: Any

    8.
    Aquarium Pewter Sand

    Perfect for decoration as well as using as a planting medium, this sand is nice and fine to act as a gravel base or on its own.

    The price is good for how much you get, as there is a good chance you will only need one or two bags for the size of your tank.

    It takes quite a bit of cleaning as it is so fine, and needs a good few hours to settle as well. Make sure you have a filter which can keep the water clear. It also goes darker when wet which is understandable but you need to think about it before buying.

    Features

    • Fine and soft for most fish

    Specifications

    • Colours: Pewter
    • Bag Size: 2kg
    • Tank Type: Any

    9.
    Carib Sea ACS00120 Crushed Coral for Aquarium

    Crushed coral won’t be for every tank, as the 100% aragonite mix is purely for tanks which need to maintain a good pH level in saltwater tanks.

    Even just the smallest bit will alter the pH level drastically, so it really does the job. This large bag could, therefore, last a lifetime. It can recreate natural reef environments, and will even look very pretty thanks to the little seashells and natural products mixed in.

    The price is quite high for a bag of its size, but it is a very speciality product so it will be worth paying that bit more for something which is quality. The aragonite gives you 25x as much buffering power compared to other coral forms, which again is worth paying for if you really care about your fish.

    Features

    • Colours: Brown
    • Bag Size: 6.8kg
    • Tank Type: Marine

    Specifications

    • High filtering power
    • Small grain size for reducing detritus build-up

    10.
    Sakana White Aquatic Fish Gravel

    A huge 10L tub if you have a lot of tank to fill, but it is also available in some smaller tubs if needed. In kilograms, this works out as double so is 20kg.

    It is bright, natural and decorative to really add a touch of class to your display. Non-toxic, it won’t damage the water pH levels or make it cloudy. Once it has had its initial clean, it will remain dust-free. 

    Each stone has a diameter between 3 and 8mm, making it safe for use with pretty much all fish breeds. It’s 100% natural, with no chemicals which can harm your fish, and it can also be used in outdoor ponds.

    Features

    • Indoor or outdoor
    • Good price

    Specifications

    • Colours: White
    • Bag Size: 1L, 2.5L, 5L, 10L
    • Tank Type: Any

    Buying Guide

    Types Of Substrate

    The main question for the majority of tanks is usually sand or gravel? There isn’t generally a rule on what you should have but think about the fish in your tank. If they are natural burrowers, sand will be easier for them to get into, especially if they are smaller. Gravel and stone could also be a bit sharp for them.

    Sand also makes for an increased surface area, in turn allowing for improved anaerobic activity. Gravel, however, comes in the most varieties, options and colours if you really have a look in mind. It is also often easier to keep clean too, especially if you will be using a vacuum.

    Other options include crushed coral gravel which can raise the pH levels of your water tank, especially handy when your fish prefer more alkaline levels. It dissolves over time, so will need replacing.

    Marbles can be found in some tanks with fish which breed regularly, as it can stop the adults eating the eggs due to lack of access when they fall. Large stones are also frequently used to keep plants safe and in place.

    Then there is a soil-like substrate, which is great for planted aquariums. It often comes in little balls as something as fine as the soil would obviously play havoc on water balance.

    There is sometimes no reason why you can’t layer different forms, although exceptions to this rule do occur with speciality materials. If you have live plants, using laterite or vermiculite soil-base can help with nutrients, and can sometimes be topped with gravel for an aesthetic look.

    Tank Type

    In general, most gravel and sand can be used in saltwater or freshwater tanks. But there may be variations which can only be used in tropical or cold water as the salt and pH levels of a marine tank could be detrimental, and likewise, the hotter temperature in some tropical may make some only good for coldwater.

    Check before you purchase your chosen substrate, but remember that if you are set on a white stone for your marine tank, there will be a form out there or in aquatic shops.

    Bag Size

    You can generally purchase gravel in all sizes. How much you need depends on how large your tank is.

    If you want to get really technical, multiply the length of the tank by the width. Divide that answer by 10, and convert into kilograms by dividing by 2.2. A 22 x 20-inch tank = 440. Divided by 10 = 44. Divided by 2.2 = 20kg.

    Any spare gravel can generally be kept for situations in which some needs to be replaced/changed or can be used as a decorative element for plants and pots.

    Other Buyers Ask...

    What is the purpose of the substrate?

    There are several reasons why your tanks should have a layer of substrate on the base.

    Tank Cleanliness

    For many, it offers a place for any waste or uneaten food particles to settle and become captured, until the time comes for them to be cleaned up. This prevents them from breaking down as much and making the water cloudy or full of ammonia.

    The gravel also acts as a natural bacteria medium, encouraging the production and growth of ‘good’ bacteria which will help your tank filter out when cleaning the water. This bacteria can also help your plants to thrive, which boosts the life of your tank.

    Fish Environment

    Some fish are benthic, so they naturally go along the bottom of the tank floor finding waste and food. Catfish and goby are two commonly found bottom-feeders in home aquariums.

    Breeds such as jawfish like having a sandy surface to dig into and hide or ‘hunt’. This burrowing can help them to feel safe, and the substrate also doesn’t reflect the image of the other fish in the tank as glass does, so they can stay hidden.

    Looks

    Of course, the substrate can be aesthetic too. You can choose the colours, styles, sizes and material type if you want your tank to have a certain look, as long as your fish will be happy with it.

    When combined with plants, hiding places, rocks and driftwood, it creates a natural mini ocean environment. A well-crafted aquarium also is said to have a positive health benefit on those who gaze at it.

    How much gravel should I use?

    It is a good idea to use an exact calculator to work out your precise amount based on the size of the tank, your fish and how many fish are in the tank. We have given the equation to use under the ‘Bag Type’ Buying Guide section.

    Be aware that too much gravel can cause too many anaerobic zones, which affect the chemical build of your tank. Wash the gravel before it is put in the tank to remove any natural dusty parts or fine bits which may not sink.

    How often will I need to replace it?

    You can’t really change the gravel in your tank every year to alter the style and colour as you would paint your living room, change your curtains or get a new set of saucepans.

    This is the environment of your fish, plus it is a lot of hard work to do this. Gravel helps act as a biological medium, for the promotion of healthy bacteria which in turn helps oxygenate the water and keep it all clean. When replacing this, you’d have to try and maintain this all which is difficult and requires a few days.

    Vacuuming it and washing sections occasionally with a dedicated gravel cleaner should be enough to keep it clean. Purchase high-quality gravel and it should remain intact and looking good for years to come.