TECHNIQUES
• Some fish (here, Sturisoma rostratum, from South America) use fine sand to hide themselves, either wholly or partially.
of sand may finish up suspended in the water. However, bottom-dwelling fish endowed with barbels seem to appreciate this type of sand. Other specific factors related to its use can be seen in the table on page 261.
affected by this when the aquarium is put into operation. Remember that it is possible to add both solid and liquid fertilizers to compensate for this deficiency. Once a good equilibrium has been achieved, the bed will gradually get richer and will start to be really beneficial to plants after about 4-6 months of operation. Hobbyists who want their plants to grow more quickly can introduce an enriched substrate at the outset. This is available, already prepared, in the aquarium trade, but you can also make your own enriched bed on the basis of a recipe used and advocated by countless fishkeepers and specialist magazines (see box below). However, beginners are advised to start with a normal or commercially enriched bed, before moving on to create specific individual substrates.
• Collecting sediment from a natural setting
Some aquarists may be tempted to collect sediment themselves from a natural setting, although in theory this is forbidden. A clean and well-oxygenated watercourse must be chosen. The granule size gradually decreases as the water flows downstream. Sediment can often be found where it has collected in the inner part of a bend in a watercourse. Enriching natural beds
Like a gardener, the aquarist can enrich these natural soils, as the most common sands, like quartz and Loire sand, are somewhat deficient in mineral elements, and so there is a danger of plants being
THE BED AND OXYGEN As a general rule, a bed must be considered as facilitating the movement of water. The water supplies oxygen to the microfauna living in it, enhancing the progress of the oxygen cycle. If the sand used is too fine, it becomes too compact to allow the water to circulate freely. This may give rise to black patches, a sign of oxygen deficiency and the presence of toxic substances.
MAKING AN ENRICHED BED The classic recipe is: - 10% clay: this enhances the use of mineral salts by the plants; - 40% heath-mold without manure: beware of false heath-molds and various types of compost; - 50% unprocessed Loire sand: if this is not washed, it contains mineral elements. Mix the ingredients and put a 1 cm layer of quartz sand on the bottom, followed by 2-3 cm of the mixture and pack down thoroughly. Cover this with a few centimeters of quartz sand. Obviously, you will not be able to dig around in this kind of substrate, so do not forget to put the decor in place beforehand. Do not use an under-gravel filter with this substrate. It might be argued that it is not oxygenated, as we have previously recommended, and this is true. However, it does produce other reactions, and accidents with it are very uncommon. Some aquarists have reported that this type of bed can remain effective for more than one year, sometimes more than two. Even if you are reluctant to apply this method directly in an aquarium, it can nevertheless be used in small aquatic jardinieres containing plants. This certainly has practical advantages - they are easy to move - but you will have to camouflage the bed.
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