Watts per gallon rule

[Trout11B]

I've seen in mentioned throughout the forums in regards to lighting in the planted tanks, but why does the watts per gallon rule not apply to smaller tanks? I feel like in the smaller tanks you would need even less lighting than you would for a deep tank.
If someone could answer this for me, or explain the reasoning behind the entire rule that would be great, because so far I can't find a clear answer to it. One of the reasons I'm asking is because I have a small ten gallon that I have just began planting, and would like to make sure I have sufficient lighting for at least medium light plants.
Currently, the set up is a standard ten gallon hood with two 10 watt CF's screwed into the top. Eventually, in the spirit of being green (i.e. more green in my pocket) I would like to switch over to LED's which help with efficiency as well as lasting longer.
Thanks for the help.

 

[BBradbury]

Lighting Question

Hello Trout...

The "Watts per Gallon Rule" is helpful if you use standard florescent lighting. Ideally, you want 1.5 to 2 watts per gallon of tank volume, but to do this, you generally need a fixture that will hold 2 or more bulbs. If you get the watts up to this level, you'll be able to grow most of the aquarium plants on the market. Florescent bulbs are available at any of the local hardware stores. GE makes a good aquarium plant bulb for just a few dollars per bulb and they last well over a year.

B

 

[Rivercats]

Florescent lights are the only ones that the watts per gallon rule can really be applied. Now a days with all the different types of lighting available (T5HO, LEDs, Metal Halides) you have to go by Par, Lux, and Lumens.

 

[Trout11B]

Thanks for getting back everybody.

So, what I'm reading here is that I would still go with the wpg rule based on the fact that I have CF's. However, if I do make the transition to an LED fixture ill be looking for other factors not really watts.

I've read some on PAR and lumens, but its still beyond my comfortable level of research on the matter.

Last thing, so by my ten gallon being lit by two 10watt cf's where do I stand on the lighting side of things.

 

[Rivercats]

There are alot of people on here that use CFL's on 10g's and they get great plant growth.

 

[Mrs.h2012]

There are alot of people on here that use CFL's on 10g's and they get great plant growth.

I actually use cfl's on a 55g tank for low light plants and it's working perfectly fine for me; my tank is open top and I use clip on lamp fixtures as I have no hood or canopy. I have a 10g I would really like to try the cfl lights on and see how it goes.

 

[Mrs.h2012]

Thanks for getting back everybody.

So, what I'm reading here is that I would still go with the wpg rule based on the fact that I have CF's. However, if I do make the transition to an LED fixture ill be looking for other factors not really watts.

I've read some on PAR and lumens, but its still beyond my comfortable level of research on the matter.

Last thing, so by my ten gallon being lit by two 10watt cf's where do I stand on the lighting side of things.

You would have 1 watt per gallon. How to get the answer is basic division.. It's (total number of watts)/(tank volume.. In your case 10). So as you see.. Your answer is 1 watt per gallon.

 

[Trout11B]

You would have 1 watt per gallon. How to get the answer is basic division.. It's (total number of watts)/(tank volume.. In your case 10). So as you see.. Your answer is 1 watt per gallon.

So you don't add 10 watts plus 10 watts based on the number of bulbs. It's ten watts all the way through?

 

[Cichlid Kid]

I'd like to know that as well. I always assumed as the OP, and that they would have 2 wpg?

 

[Rivercats]

In the old watts per gallon you added up the sum total of all bulbs. So 2-10w bulbs would be 20.

 

[Rivercats]

If you had 20w in a 10g it would be 2w per gallon.

 

[Mrs.h2012]

So you don't add 10 watts plus 10 watts based on the number of bulbs. It's ten watts all the way through?

My mistake, I didnt see where there was already 10 watts present. My mistake.

 

[Trout11B]

Alright! Everybody makes mistakes, especially on the Internet, haha. Thanks for your help everybody.

One last question, perhaps I missed it in the previous posts, but with 2 wpg am I in the mid light range?