Substrates for the Home Aquarium
By
Rajendra Kumar G. G.
Originally published in Infoquaria. Aquarist Society of Karnataka,
India
Aquarticles
Aquariums need substrate as a rooting medium for plants and as a bed for beneficial
bacteria for nitrogen cycling. Every naturally occurring aquatic environment has a
substrate of some form or other. It also serves as a natural looking background to
highlight the colours of the plants and fish. Certain fish varieties depend on the
substrate for their feeding or breeding activities.
Substrate colour
Substrate may be of any colour from almost white to black. Darker substrates will hide the
detritus, while light coloured substrates will look unsightly when detritus collects. The
substrates in naturally occurring environments are generally dark, often covered by fallen
leaves and twigs. The substrate colour will influence the coloration and behaviour of the
fishes. Colours of neon types of fishes will be highlighted by a dark background.
Substrate particle size
For optimum results with plants, sand for the substrate should be between 1.5 and 3mm in
diameter. This size of substrate particles will encourage the plants' roots to easily
penetrate the substrate and allow the substrate to "breathe". Smaller substrate
particles will tend to clump and compact along with mulm and render the substrate
anaerobic. Bacterial action in anaerobic substrate will produce hydrogen sulphide,
resulting in a smelly black mess. Larger particles will prevent the roots of plants from
penetrating, resulting in slow or stunted growth. Fish such as goldfish have a habit of
constantly sucking up bit of sand and spitting it out, and if the substrate is too fine
the water will cloud up quickly. Extremely tiny particles in suspension will irritate the
mouth cavity and gills of fish.
Substrate material
Almost any gravel can be used as a substrate for the home aquarium. The gravel material
should chemically inert - i.e. it should not chemically react with and alter the water
properties. The gravel particles must not have sharp edges that will injure bottom feeding
fish. Water worn particles are the best; they will have rounded edges. Avoid marble chips
as they consist of a form of calcium carbonate which will slowly dissolve in water and
increase the carbonate hardness (KH) and render the water hard. Avoid coral and decorative
sea shells for the same reason.
Substrate depth
The substrate should be sufficiently deep to allow the plants to root securely and grow.
It should not be too shallow or too deep - the depth of substrate in an aquarium should be
in proportion to its height for aesthetic reasons. The depths given below are a
suggestion, arrived at by my experience.
Tank Depth of
Height Substrate
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12" 2"
15" 2.5"
18" 3"
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Preparation of sea sand as a substrate for the aquarium
Some stores sell untreated sea sand, or if you live in a coastal area you may wish to try
making your own substrate from sea sand. However, sea sand has a large amount of sea
shells mixed along with the sand. Shells basically consist of calcium carbonate which will
eventually dissolve in the aquarium water making the water very hard and alkaline.
Alkaline water is stressful for many fish and should be avoided. For use in fresh water
aquariums the sea sand should be cleaned of all bits of sea shells:
You will need -
1. A couple of large wide mouthed plastic containers and a large bucket.
2. Industrial HCl (hydrochloric acid), which is sold by weight. You will need at least
30-40 Kgs / Litres.
3. Rubber gloves.
4. Non-metallic stirrer - a sturdy bamboo or stick will do.
5. A pump type of plastic siphon, available at automobile stores.
6. Plastic mug.
7. Sieve material suitable to pass 1.5mm, and a second one for 3mm.
Procedure -
1. Remove all bits of twigs, stones and other large objects.
2. Strain the sand through a sieve that will pass particles that are smaller than 1.5mm or
1/16" in diameter. Discard the sand that has fallen through the sieve.
3. Strain the remaining sand through a sieve that will pass particles that are smaller
than 3mm or 1/8", and discard the larger size sand that remains. You now have
sand particles that are bigger than 1.5mm and smaller than
3mm in diameter.
4. This step must be done outdoors and in a well ventilated area. The acid fumes
are harmful to plants and animals. Do not handle the acid with your bare hands. If
you must put your hands in or make contact with the acid, use rubber gloves. If any
acid splashes on you, wash with plenty of water.
Put a small quantity of sand (one or two
mugs full) into a wide rim plastic container. Add a little
water, and siphon out an equal amount of
industrial grade hydrochloric acid into the container. You will notice an immediate
fizzing - this is shell bits reacting with HCl and producing carbon dioxide and calcium
chloride as a side product. Keep adding acid until the fizzing completely stops. Leave the
sand soaking for some time. Drain out the acid into a second container. Rinse out the
first container with water and pour the processed sand into a bucket for further washing
later. Leave this sand in water to soak out acid that has seeped into the cracks in sand
particles. Now add more unprocessed sand to the second container and leave for some time
till fizzing stops or overnight to completely exhaust the acid. Drain the second container
out and add a little water and fresh acid, and repeat the above steps. Accumulate the
processed sand till you have enough for your aquarium or you have exhausted your
unprocessed sand.
5. Wash the processed sand with many changes of water and vigorous stirring. To be
completely sure that all the acid is gone, check the rinse water with litmus pH paper that
indicates acidic/alkaline. Keep washing till the litmus paper does not change colour. It
is better to err on the cautious side than have HCl acid in your aquarium..
?
The author Raj Kumar is a regular
contributor to Aquarticles. His articles are:
New Aquarium Blues: The Nitrogen Cycle
So You Want to Grow Plants in Your Aquarium!
Substrates for the Home Aquarium
Imaginative ideas for Your Aquarium
Fishy Cartoons (by his daughter, Pia)
There is an article about Raj in the People Section: People/Raj Kumar
Raj runs a Yahoo Group for Indian aquarists, "Aquarists
of India"
Here is a link: http://groups.yahoo.com/group/a-s-k
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