Wattage Per Gallon Rule?

[tcy81]

hi all ,
I am abit confuse, WPG rule, your volume is calculated based on your actually tank size or the actual water volume in your tank ?
thanks

[|squee|]

Actual tank size I believe.

[tcy81]

Actual tank size I believe.

thanks for the information.

[taz_boy]

i take length of tank x width of tank x height (bottom to water level) to calculate.

[tawauboy]

it is not a rule but a guideline.
and us gallon is used not imperial gallon.

[tcy81]

it is not a rule but a guideline.
and us gallon is used not imperial gallon.

ops, ya guideline.

[Shadow]

by the way it does not work with small size tank. My guess is different plant have different light threshold where if the light intensity below that, it won't grow or die.

[juggler]

It also depends on tank size and the plants grown. My office 3.5ft (56g) tank has light loving plants and it is using 3.8W/g. My home 5ft (128g) tank has lower lighting plants and it is using slightly less than 2W/g.

Having said that, here's another article of interest: Lighting as a Function of Tank Size in the Aquaria of Takashi Amano

[Shadow]

wow , I need 31watts for my 2 gallons tank, using that calculator

[tcy81]

It also depends on tank size and the plants grown. My office 3.5ft (56g) tank has light loving plants and it is using 3.8W/g. My home 5ft (128g) tank has lower lighting plants and it is using slightly less than 2W/g.

Having said that, here's another article of interest: Lighting as a Function of Tank Size in the Aquaria of Takashi Amano

thanks for the article

[tcy81]

i think for larger tank, for example 4ft x 2ft x 2ft is 120gal. is based on full volume of the tank. and you use 2 x 150w MH light.
WPG is 2.5 only. so larger tank should have lower WPG.

[Ah_ZhaN]

It also depends on tank size and the plants grown. My office 3.5ft (56g) tank has light loving plants and it is using 3.8W/g. My home 5ft (128g) tank has lower lighting plants and it is using slightly less than 2W/g.

Having said that, here's another article of interest: Lighting as a Function of Tank Size in the Aquaria of Takashi Amano

Thanks Peter, that is a good link and guide.

wow , I need 31watts for my 2 gallons tank, using that calculator

I am aleady using 44watts (24watts + 20watts) for my 6 gallon tank (25Litres). But my rotala sp 'red' is still... ...pinkish.

[yeoyl87]

6 gal is around 1ft cube right? The website said that my tank required 55W...still scratching my head on how to fit in 55w....

[planted86]

but what if i have a slim and tall tank but the same volume as a wide and short tank?? FOR EXAMPLE i'm using 2X 39W T5 for my standard 3ft(L) X 1.5ft(W) X1.5ft(H) tank but can i use it for a tall tank like 3ft(L) X 0.5ft(W) X 4.5ft(H) that has the same volume but taller height will the light be able to penetrate to the bottom of the tank???

[oblivion]

theres another watt per litre rule to cater for tanks

also a watt vs surface area rule which may make sense

search around
i remember a thread not very long ago discussing all these

[Shadow]

I thing the best is using water proof light intensity meter. It will not measure the spectrum intensity but at least we can get the correct wattage. Up to the scaper to make sure that the light he/she used have the right spectrum.

[salexjared]

Interesting that a small tank requires much higher light requirement.

BUT for small tank, the standard available lightings (from LFS) is way below that requirement (usually around 9-13W) and does not have high output.

So hobbist that use small NANO tank must scratch their heads to figure out how to do it (still not sure if we really need 60W!!!)

I use a 2, 2 feet lights to generate about 48W of lighting (Still not enough by the calculator).

However I have recently dropped back down to 24W as I find that with 24 or 48W the plants (mostly mosses, ricca and tiger lily) that I have does not differentiate much in growth and health and I save the headache of controlling algae bloom.

[soulfinder78]

i remember reading in some article that for T5 lights, the 2WPG does not apply. can bros here advise on this issue too?

[yeoyl87]

The calculator said I need 179watt for a 3ft tank. I assume 4x 39w T5HO is almost sufficient? I am planning to plant glosso, ferns, stems plants.

[Shadow]

Interesting that a small tank requires much higher light requirement.

That is why MAYBE each plant has their own light threshold. If the light below that certain level, photosynthesis will not produce enough to support the plant, thus it start melting.