 Lighting
contributed by Dennis Bednarek and Hardjono Harjadi
All plants have a cycle in which during the light hours they use CO2
and release Oxygen through a process called photosynthesis. During
the dark hours the opposite occurs and the plants use Oxygen and
release CO2 in a process referred to as respiration. In most aquarium
plants the period of photosynthesis in nature is between 10 and 12
hours which should be duplicated as closely as possible in the aquarium
to allow a balance between the two processes.
In nature some plants are located in large open ponds and receive a
large quantity of light, others are located in triple canopy jungles
and receive low quantities of light. Each variety of plant has its own
light requirements and for best aquarium results these requirements
should be met as much as possible. In this FAQ we will divide the
plants into groupings that require low light, low to moderate light,
moderate to bright light, and bright light. There are also bog plants
that are often sold as aquarium plants which we shall not cover in this
FAQ except to mention here that their lighting requirements are usually
greater than even the bright grouping.
Fluorescent lighting is the most economical means of establishing a broad
spectrum of light in an adequate quantity for the survival of aquatic
plants. It is recommended that broad spectrum tubes be used to produce the
proper lighting similar to the varieties sold in plant stores and aquarium
stores, rather than the standard cool white bulbs available at hardware
stores. People have had good luck with almost any of the "full spectrum"
or plant specific bulbs (Vita-Lite, GE Chroma 50 and 75, Phillips
Agro-Lite, UltraLume and Advantage X). The more expensive "three phosphor"
bulbs like Triton and Penn-Plax Ultra-TriLux seem to have a more realistic
color rendition. You can combine different types of bulbs to achieve the
same results but the tri-phosphor bulbs are generally much brighter than
less expensive types. Note that fluorescent bulbs age and will lose
intensity over time. It is recommended that bulbs be changed every 6-12
months (try to have the bulbs on a rotating schedule, i.e., a new bulb
every 3 months rather than 2 new bulbs every 6 months).
When calculating the amount of lighting you will need there is a general
of thumb. First multiply the surface area of the aquarium by the distance
from the light source to the top of the gravel. Then depending on the
type of plants you desire multiply this by one of the factors given below.
Low light plants 0.08
Low to Moderate light plants 0.12
Moderate to Bright light plants 0.18
Bright light plants 0.27
This will give you the ideal watt hours of fluorescent lighting that you need.
Divide this number by 11 and you now have the approximate total wattage of
lights you need. Unfortunately this number may not be equal to what is
available in bulbs so find the combination of wattage that will most closely
match this requirement and adjust the available time to match the watt hour
calculation.
Example:
required watt hours is 1440, divided by 11, is 131 watts of power.
since the closest is 3, 40 watt tubes we divide 1440, by the
120 watt total and we find we need 12 hours of lighting at this
level.
Warning:
A common mistake is to deviate greatly from the 11 hours of light
to compensate for low or high wattage. If the light time exceeds
16 hours more wattage should be added to reduce this time, Or if
the light time is less than 8 hours less wattage must be used
to allow adequate time for photosynthesis.
When selecting plants also keep in mind that large center plants will
shade the smaller plants under them and that higher light requiring
plants should not be selected for small filler plants.
Many older or cheaper fluorescent fixtures require you to hold down a
pushbutton for a few seconds to turn it on, thus preventing you from plugging
it into a timer. You can convert such a fixture into an auto-starting model
by clipping two wires and buying two new parts. You need a starter,
a little gray can-like thing found in any hardware store. Make sure to buy
the correct one for your size bulb; they say which is right on the package.
You also need to buy a socket for the starter, or find some way to
attach the wires directly to the two terminals on the starter. The sockets can
sometimes be hard-to-find, but big hardware stores might have them, and
mail-order fish suppliers (MOPS, for instance) can sell you both parts as
a kit.
Refer to the diagram below:
line switch line plug
\ Hot wire /-----|
+------------ballast-------------o \____________/ |--- -> smaller plug
| --\ |----- -> longer plug
| --------- | \-----|
| ----------------|starter|---------------+ +-----------------------+
| | --------- | |
| | +---------------------+ |
| | | |Neutral
| | |-----------------------------------------------------| | |Wire
| +---| |---+ |
| | light tube | |
+------| |--------+
|-----------------------------------------------------|
The two leads you want to connect to the starter are connected to the
pushbutton; usually they're red. Clip them at the pushbutton and attach
to the starter socket. That's all!
 CO2 Injection
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