Watts per gallon question
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malkore
Aquarium Advice Addict
Since the WPG rule is just a loose rule, which can really only be applied to normal fluorescents and a standard rectangular tank that's between 20-90 gallons...just go off the total capacity.
malkore...Good to know, thanks. When you say 'normal fluorescents' does that mean that the WPG rule doesnt apply to compacts? I read one of your earlier posts about lumens...is that a better measure when talking about compacts?
malkore
Aquarium Advice Addict
Lumens are indeed better, since that's a measure of light output, where as watts is a measure of energy used by the ballast to power the lights.
Power compacts produce more lumens per watt than NO tubes. Ordinary incandescent lights are the least efficient of all. PC adn VHO are about the same. Metal Halide is less efficient than PC/VHO, but since you get such high wattages in a small space, their brute force output makes up for the less efficient output (which is still better than incandescent and NO fluor.)
You can still use the WPG, but with PC's and VHO's you can cheat. In other words, there's no need to go over 3wpg with PC's, but with NO's you might need 3.5wpg for certain plants. At 2.0wpg of PC you really need CO2, but it's 2.5wpg for NO's.
Power compacts produce more lumens per watt than NO tubes. Ordinary incandescent lights are the least efficient of all. PC adn VHO are about the same. Metal Halide is less efficient than PC/VHO, but since you get such high wattages in a small space, their brute force output makes up for the less efficient output (which is still better than incandescent and NO fluor.)
You can still use the WPG, but with PC's and VHO's you can cheat. In other words, there's no need to go over 3wpg with PC's, but with NO's you might need 3.5wpg for certain plants. At 2.0wpg of PC you really need CO2, but it's 2.5wpg for NO's.
jibboo
Aquarium Advice Freak
ok, so for example ... I have a c-usa satellite 2x65w PC fixture over my 55 gallon, so by what you're saying I should look into doing some CO2? I considered trying the DIY CO2, but was wondering how do you regulate the flow into the tank?
Also, is there any difference in calculations if you have a glass canopy between your light and the tank? I just recently took out my glass canopies (since they get smudged and water stained all the time) and I notice that my tank looks much brighter w/out the glass canopies ... so does that have any impact on calculations? I can't imagine I'm getting the same light output into my tank when my canopies are deflecting/defracting/whatever some of the light.
Also, I read somewhere that ppl don't think there is any difference in light between the 55watt PC and 65watt PC ... do you have any knowledge about that?
Also, is there any difference in calculations if you have a glass canopy between your light and the tank? I just recently took out my glass canopies (since they get smudged and water stained all the time) and I notice that my tank looks much brighter w/out the glass canopies ... so does that have any impact on calculations? I can't imagine I'm getting the same light output into my tank when my canopies are deflecting/defracting/whatever some of the light.
Also, I read somewhere that ppl don't think there is any difference in light between the 55watt PC and 65watt PC ... do you have any knowledge about that?
malkore
Aquarium Advice Addict
with 2x65watt PC's on a standard 55, I'd look into some CO2, especially if you feel the plants look bad, aren't growthing well (leggy instead of bushy) or if you have any kind of algae problems.
dirty canopies will affect light penetration, but clean ones shouldn't matter that much.
55 and 65 watt bulbs should put out different amounts of lumens...the 65's should run hotter, since they're the same size as a 55, but use 10 more watts of power.
However, it'd be fairly hard to visually see a difference since its so bright to start with. I'm sure a light meter would read different outputs.
10watts won't matter much to a plant, but 20 watts (2 bulbs) could make the world of difference on some plants (carpet plants like glosso, or harder plants like rotala macranda)
dirty canopies will affect light penetration, but clean ones shouldn't matter that much.
55 and 65 watt bulbs should put out different amounts of lumens...the 65's should run hotter, since they're the same size as a 55, but use 10 more watts of power.
However, it'd be fairly hard to visually see a difference since its so bright to start with. I'm sure a light meter would read different outputs.
10watts won't matter much to a plant, but 20 watts (2 bulbs) could make the world of difference on some plants (carpet plants like glosso, or harder plants like rotala macranda)
jibboo
Aquarium Advice Freak
I had (2) 15watt lights on in addition to the satellite, but it just got to be a pain to get into the tank and the canopies were always water stained (not like I'm cleaning them every day) ... but since I don't have any jumpers (to my knowledge), I was messing around with moving the satellite into the middle of the tank (instead of in the back with the 2 15watt lights in the front) and I think the tank looks much brighter and better.
thanks for the advice, maybe I'll go track down the lumen ratings for the lights I have in there ... could you point me to any resources that calculate light amounts based on lumens instead of watts? (is there even such a thing?)
thanks for the advice, maybe I'll go track down the lumen ratings for the lights I have in there ... could you point me to any resources that calculate light amounts based on lumens instead of watts? (is there even such a thing?)
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