DURATION OF LIGHTING
High-quality lighting serves no purpose if it is switched on only for a few hours
a day; by contrast, there is no sense in providing illumination for 15 hours a day
if the lighting is inappropriate. One will not compensate the other under any circumstances.
Once the lighting is suitable, both qualitatively and quantitatively, you must decide
for how long you are going to switch it on.
Some, generally small, aquariums, include basic equipment.
The lighting is therefore incorporated into a hood which cannot get splashed by
the water..
In tropical regions, the day lasts for approximately 11 to 13 hours, and this
is what wild plants and fish are accustomed to. The situation is different for plants
and animals raised in captivity, which can tolerate different lighting, but always
within the bounds of reason. An aquarium can be lit for 13 hours a day, but some
hobbyists exceed these limits, as they get used to turning the aquarium on when
they get up and switching it off late at night. In this way the lighting can be
on for stretches of 16 or 17 hours, which is far too much. It does not especially
harm the fish, but it nevertheless changes the balance of the aquarium, and is particularly
conducive to the development of algae. It is advisable to keep the lighting on for
about 10 hours and switch it off at around 10 or 11 o'clock at night. The use of
programmed electrical clocks facilitates this operation, and particularly avoids
any abrupt and unnatural transition from dark to light, which can be harmful to
some fish in the aquarium. In this way, the aquarium will receive the light of the
new day first, followed by its own lighting. Once the artificial lighting has been
switched off at night, the tank will still be able to take advantage of the ambient
lighting.
A blue tube can be added to daylight lamps to recreate the
lighting in reef areas.
It is also possible to create a program that switches the fluorescent tubes on
and off, one after the other, using several timers, thereby recreating, to a certain
extent, sunrise and sunset.
The ideal lighting program would therefore switch on the room's ambient lighting
in the morning, or allow the dawn light to exert its influence, then turn on one
tube about 1 hour later, and finally switch on the other tubes a little later. At
night, it would first turn off some of the tubes - with just one remaining lit -
then, a short while later, the final tube. and. finally, the ambient lighting in
the room. Last but not least: do not interrupt a daytime light. Several hours of
darkness, whether total or partial, unbalances the growth of plants and the behavior
of fish.
GOOD LIGHTING REQUIRES GOOD INSTALLATION
The positioning of fluorescent tubes in a hood
The fluorescent tubes must be distributed with, optimally, a distance of 8-10
cm between them (diagram 1). In the fitted aquariums that are commercially available,
the length of the tubes matches that of the aquarium, although it is noticeable
that the sides of the aquarium receive a little less light than the center or the
front and back. Problems arise when the tubes are markedly shorter than the tank,
which can occur in commercial aquariums with unusual dimensions, or in homemade
ones. If the tubes are all centered, then there is a space on both sides, which
may disadvantage plants on the sides of the tank. A partial solution to this problem
is alternating the position of the tubes along the sides (diagram 2).
Another option is the use of tubes of different lengths, making sure that they
are arranged to cover the whole surface of the tank and that their total intensity
is sufficient.
How many fluorescent tubes are needed for good illumination?
The number of tubes required depends on their intensity and the size of the aquarium.
Here are some indications for water of a maximum depth of 0.5 m:
These are the data, according to some standard dimensions, for a normally planted
tank:
Good lighting must both cover the needs of plants and satisfy
the visual sense of onlookers.
|
