Lighting Analysis

**maverick** · 30th Oct 2002, 09:58

Guys guys guys,

Was wondering of the 3W/gallon theory for adequate lighting for planted tanks. I am thinking of setting up a 2nd tank which will be 1.5ftx1.5ftx2ft(tall)tank. Its a cube except that its taller!!!
This will work out around 105W for the tank... but will this light be able to reach the bottom of the tank?

If I set up a shallow tank say 4ft length x 2ft wide x 1ft height, will the normal 3W/gallon apply or I can cut it down to 2W/Gallon? The 1ft height will be reduced due to the substrate and gravel height....

**maverick** · 30th Oct 2002, 09:58

Guys guys guys,

Was wondering of the 3W/gallon theory for adequate lighting for planted tanks. I am thinking of setting up a 2nd tank which will be 1.5ftx1.5ftx2ft(tall)tank. Its a cube except that its taller!!!
This will work out around 105W for the tank... but will this light be able to reach the bottom of the tank?

If I set up a shallow tank say 4ft length x 2ft wide x 1ft height, will the normal 3W/gallon apply or I can cut it down to 2W/Gallon? The 1ft height will be reduced due to the substrate and gravel height....

**maverick** · 30th Oct 2002, 09:58

Guys guys guys,

Was wondering of the 3W/gallon theory for adequate lighting for planted tanks. I am thinking of setting up a 2nd tank which will be 1.5ftx1.5ftx2ft(tall)tank. Its a cube except that its taller!!!
This will work out around 105W for the tank... but will this light be able to reach the bottom of the tank?

If I set up a shallow tank say 4ft length x 2ft wide x 1ft height, will the normal 3W/gallon apply or I can cut it down to 2W/Gallon? The 1ft height will be reduced due to the substrate and gravel height....

**maverick** · 30th Oct 2002, 09:58

Guys guys guys,

Was wondering of the 3W/gallon theory for adequate lighting for planted tanks. I am thinking of setting up a 2nd tank which will be 1.5ftx1.5ftx2ft(tall)tank. Its a cube except that its taller!!!
This will work out around 105W for the tank... but will this light be able to reach the bottom of the tank?

If I set up a shallow tank say 4ft length x 2ft wide x 1ft height, will the normal 3W/gallon apply or I can cut it down to 2W/Gallon? The 1ft height will be reduced due to the substrate and gravel height....

**sherchoo** · 30th Oct 2002, 12:43

Normally the guide is based on the volume. So no matter what height you have it will still base on the volume. Another factor is the type of plants and how heavily you're planting them.

It's quite safe to say that for florescent lighting 2ft high is ok.

**tawauboy** · 30th Oct 2002, 13:24

i came across an article before which calculate the amount of light required.
it mentioned about taking tank surface area and multiply with distance from light to substrate. then multiply with a factor. this factor has 4 or 5 values depending on the type of plants.
this is off my head so can't provide much details.

will try to dig out the article and post details.

**tawauboy** · 30th Oct 2002, 19:30

ok.
think the source is thekrib.com

the procedure is
1) surface area x distance to top of substrate
2) multiply with one of the following factors
low light plants - 0.08
low to moderate light plants - 0.12
moderate to bright light plants - 0.18
bright light plants - 0.27
3) the figure you get will be ideal watt hours of fl/pl light
4) divide by 11 (think author/s recommend 11hrs of light)

example:
required watt hours is 1440, divide by 11, you'll get 131watts. closest will 4 tubes of 36watt tubes.
so take 1440 watt hours and divide by 144watts, so you need to to leave light on for 10 hours.
add more tubes if light hours exceed 16 hours and use less tubes if light hours is less than 8 hours.