Watts vs. Lumens

[ebola]

Hi all,

I've been reading about setting up a planted tank, but am looking to this on a budget. I'm going to make my own hood, and it looks like the cheap way would be to use those energy efficient bulbs that they tell you swap the incandescents out of your home's lights with. But these throw off the whole 3 Wpg ratio that everyone recommends. Is there any reason you can't just use lumens as a guide instead?

 

[Notophthalmus]

Lumens are the important measurement. People just use watts because it's printed right on the package where you can see it, and is easy to remember.

 

[ebola]

Ah, thanks a lot notopthalamus. If this turns out OK, I'll put up (crummy) pics and a guide.

 

[Cory Keeper]

back when T12's were being used, yeah, use Watts. With more energy effecient lighting such as CFLs, T8's and T5's I would focus more on the lumen output, it can give you a general guide on how many bulbs you may need.

 

[Fordtrannyman]

Hi all,

I've been reading about setting up a planted tank, but am looking to this on a budget. I'm going to make my own hood, and it looks like the cheap way would be to use those energy efficient bulbs that they tell you swap the incandescents out of your home's lights with. But these throw off the whole 3 Wpg ratio that everyone recommends. Is there any reason you can't just use lumens as a guide instead?

This article may help you.
http://www.aquabotanic.com/lightcompare.htm

 

[plantbrain]

Well, lumens is a measure of our eyes, not what the plant uses, needs etc.

PAR of PFFD are typically used in plant sciences, never lumens.
Light makers use lumens because it's what we see and most lights are made for us, not to grow plants:idea:

Simply taking a PAR meter around a tank will show how and why the issue is far more complex and involved each tank's unique light field.

And every tank will be different through totals and through time and where the plant actually is(plants grow to the light and as such, the levels of PAR also changes , sometimes 50-300% in one day in some cases).

So lumens does not tell you much more really, than watts /gallon rules when it comes right down to it. You go from errors of 1000X down to 800X:silly:

But watt/gal is easy and it's never failed me on standard tanks from 10-300 gallons.

Regards,
Tom Barr

 

[jones57742]

Tom you really are a plantbrain (including an energy emission and detection brain) and maybe you can help with my thinking (I apparently do not know where to look in the literature).

I have not been able to understand the W/G when fluorescent is compared to MH due to efficiency.

I believe that the energy spectrum emitted by bulbs which are assigned K values only approximates the spectrum emitted by a black body at the K temperature. Is this true?

I believe that the quality of light emitted by a MH bulb is better than the quality of light emitted by a fluorescent bulb with identical K values due to the gaps in the energy gradient produced by the phosphor employed in fluorescent bulbs. Is this true?

Please excuse me if much of my terminology in the above three questions is incorrect.

TR

 

[Mgamer20o0]

But these throw off the whole 3 Wpg ratio that everyone recommends.

a point people didnt hit on is there isnt a magical wpg number. it really depends on what you want to do. you can have a very nice low light set up if thats what you want.