Lighting Questions

[amf17]

Here are the goals for my tank

Twenty gallon light to moderately planted tank.
Low to medium lighting level using compact fluorescents(see below for questions)
DIY co2 at 20ppm
only adding trace elements every few days
Macro's will be provided by food and waste

Lighting questions...

I keep reading about watts per gallon on the internet everywhere. This doesn't make sense to me because you can buy compact fluorescents that are 13W that have the same light output(lumens) as a 60 watt incandescent. Can someone clarify this??? Wouldn't it be more appropriate to say lumens/gallon???

I would like to have a low to medium light level, which i've read is 1-2W / gallon. If i'm using compact fluorescents, what would be the appropriate bulb to use Possibly a combination of two???

23W 1600lumens 6500K
23W 1600lumens 5000K
23W 1600lumens 2700K
13W 850lumens 6500K
13W 850lumens 5000K
13W 850lumens 2700K
9W 550lumens 6500K
9W 550lumens 5000K
9W 550lumens 2700K
5W 250lumens 2700K

 

[Colin_T]

watt would be the appropriate bulb to use?
sorry couldn't resist that

don't bother about any light with a Kelvin (K) rating below 5,000K as the colour of the light will look crap and it won't be that good for the plants. Natural sunlight has a Kelvin rating of about 5,700K so try to get lights with a Kelvin rating between 5,000 & 10,000K.

The higher wattage generally equates to a higher lumen . This simply means more light output from the globe but at the expense of using more watts (more power consumed for the extra light).

I would get a couple of the "23W 1600lumens 6500K".

re: 13w compact fluoro vs 60w incandescent. Basically a 13w compact fluoro will provide the same amount of light as a 60w incandescent globe but it will use 13watts of power instead of 60watts. It will be cheaper to run and have a better colour of light.

Incandescent globes usually have a Kelvin rating below 3,000K so the light will look more yellow. The compact fluoro with a Kelvin rating of 6,500K will look white because it produces a more balanced colour.