Tropical Fish Keeping - Aquarium fish care and resources

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-   -   how much light is too much? (

dave1 02-16-2007 12:51 AM

how much light is too much?
well im gonna try to change my reflector from a 20w halogen lamp to the energy saving lamps, they r equal to 60w but only consume 14w and they say they r "DAY LIGHT" lamps, i have a 4 pack of them and 3 light sockets

is 2 good enough or should i put 3 in?

tank is a 29 gallon tank that i am converting from fake plants to real ones.

2 would be 4.1WPG and 3 would be 6.2WPG

dave1 02-16-2007 01:28 AM

if it goes by consuming wattage then with 2 bulbs i will have approx 1wpg and w/ 3 i will have 1.4 WPG


The intensity of the light is another major requirement. Plants take millions of years to adapt to the light of their native surroundings. Many species of tropical plants, especially the red leaf type, are very much light lovers. Others, for example, like the species Cryptocoryne will do great in shade.

For fluorescent lights with a daylight spectrum, the rule of thumb is 1 watt for every two quarts of water. Energy efficient lamps have a higher out put. Spiral fluorescent tubes are substantially brighter than straight ones. The luminosity of lumilux tubes is about 30 % greater. For these lamps, 0.3 watts per quart of water is more than sufficient.

The deeper the light penetrates into the water, the more it diminishes. That is, the top of the tank will get more light. If your large background plants are thriving and the small ones in front are not, you should choose different types of tubes that are more luminous. You could also install another fluorescent tube. The same is true with a tank that has been prepared with peat. The brownish color of the water causes more light to be absorbed and less reaches the plants.

Aquaticmoon 02-16-2007 09:31 AM

Do you have a link to the lights that your talking about? This would give us a better ideal of what you are trying to do.

If your new to the plant hobby, IME, 1.5-3wpg is a good starting point for a 29 gallon tank.


2 would be 4.1WPG and 3 would be 6.2WPG
with this much light your are going to need a good fert program and CO2.
This is also more light than most new plant hobbies can work with.

fish_4_all 02-16-2007 02:20 PM

The screw in compact flourescent bulbs don't give off that much light unfortunately, otherwise I would use them now for my higher light needs.
60 watts of light may equate to 180 watts total but with restrike, dispersion and the lack of good effective reflector they will not require CO2 for the tank. I have a friend that uses 2 60 watts bulbs over a 10 gallon tank and grows plants well but doesn't need CO2.

I would say the equivelant light is only going to be about 25% so a 60 watt bulb is only going to give you a rating of 15 watts or basically the usage watts as Dave1 stated. Mess with it and see what it can grow, you may only need 2 of them or you may need all 4 to get the plants to grow. Screw in compacts are a new thing and there is a lot of information to still be gathered in their effectiveness and equivelant watts for aquarium uses.

Now a bank of these lights over a 55 gallon tank, say 6 of them with a good white background and an enclosed fixture might actually be enough light. It is just too hard to guess. Give it a shot and let us know how it works. I wish I could afford a water proof light guage to test the light levels but then I couldn't afford to feed the fish. :shock:

Laying them sideways and trying to make sure that the rods of the bulbs are parallel to the surface of the water may help some but again, it is all speculation.

herefishy 02-21-2007 03:52 PM

Wattage has nothing to do with the amount of light in an aquarium. Wattage is the amount of energy it takes to create the disensed illumination. Lumens is what is important. How many lumens does the lamp give off? Divide wattage by lumens to determine the efficiency of the bulb. Another important item to be considered would by length of spectrum, ie. how much spectral light does the lamp give off. Is the lamp's range toward the red or the blue? Full spectrum lighting is the effect we are usually looking for. We are trying to reproduce natural sunlight.

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