“34
Major Aquarium Systems
‘
natural …marin€
environménts- because the nitrifying potential
usually low compared with that available in freshwater graVel “beds,
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due to the lack0f any appreciable inorganic surface area. Gravels in -
natural marine‘aquaria should only be shallow (idea‘lly one grain
‘
deep)since without the presence of plants or other means of
ducing’ oxygen;anaerobic conditions can easily develop and ruin the
wh01e "environment. Gravels are in fact only of limited use in natural
marine syStems“ Since most filter feeding organisms prefer to hesituated on” rock rather than On 100'se. gravel and 50me anemon€s, for
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Shallow gravel/sand layer
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Fig. 6. The marine natural-system, SÇavengers such
other crustaceans
-
search out uneaten food, while lter—feeding invertebratessuch as living jcorals
remove organic material from the water. In'this way.the nitrogen 'c'ycle'iS‘ con'1pleted, provided no heavy loadings occur; Theair-bubble column provides natural
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exchange functions andturbulence
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example, will move on to:—the wall—s
container if a suitable hard
base is not provided;
stone
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(which is
satisfactory and most anemones:W:ill:ï‘n0t.:Ch-ange: position"=:in they are
initially sited to their likigEvenw1th plenty‘:of rockasahase f0r
the filter feeders the
below sothat…the
environment must
cleanF1shandotherorgamsms wh1chd1e
must be removed… quickly
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secured from rockwork,
‘m=aterialeisuch ZL-S-"ShÊHS
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before installation.
-starfishes 4 are all useful tothe
;.and‘ are;
to gâche
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natural system, provided ofcourse,thatthereare no m1xmg 1f
cult—ieS amongst them or betweenthemandtheotherinhabitants