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Discussion Starter · #1 ·
I have an extra 28 inch 75 watt grow light bought at walmart lying around, how much extra light or wattage would this put into my 36 x 18 aquarium?
 

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Discussion Starter · #3 ·
I just doubted that it would actually give off that much wattage because I only paid like ten dollars for it, but maybe so.
 

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Is this one of those with a mutli-loop bulb (can't think of the specific name)? If so, you aren't going to be getting 75w in the tank.
 

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I guess that depends a lot on the type of reflector and the shape and also age of the bulb. Also do you know the KElvin temp. rating?
 

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I just doubted that it would actually give off that much wattage because I only paid like ten dollars for it, but maybe so.
bulbs don't give off wattage?

Main Entry: watt
Pronunciation: 'wät
Function: noun
Etymology: James Watt died 1819
: the absolute meter-kilogram-second unit of power equal to the work done at the rate of one joule per second or to the power produced by a current of one ampere across a potential difference of one volt : 1/746 horsepower

measuring a bulb's usefulness based on how much watts used to generate the light is impossible.

kelvin rating is also inaccurate and has no bearing on spectral peaks for fluorescents. 6500k can be marine oriented, just like 18000k can be plant oriented.
 

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measuring a bulb's usefulness based on how much watts used to generate the light is impossible
As a single peice of information, yup pretty useless. I don't think it's irrelevant, however. If he had said "how much light will this 28 inch walmart light put in my tank" and ommitted the wattage, we'd be worse for wear.

Lumens would be more useful, but watts is a good place to start don't you think?

As usual, a picture is worth a thousand words here :)
 

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lumens don't grow plants though. the only number that matters is par rating at standard depth (24" is good enough to cover most tanks). that info isn't present though.

that bulb would bring more par to the tank; no idea how much though.
 

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Discussion Starter · #9 ·
sorry, I made a mistake, the light is 20 watts which is a big difference, its 118 V, 60 HZ, it has two prongs on each side, and 28 inches long, I don't see a kelivin rating on the bulb, I'm assuming its probally pretty usless for my application. it's made by lights of america and it model 7020.
 

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lumens don't grow plants though. the only number that matters is par rating at standard depth (24" is good enough to cover most tanks). that info isn't present though.

that bulb would bring more par to the tank; no idea how much though.
If I am not mistaken, similar to how lumens isnt oriented towards plants response neither is par exactly. Its the best thing to go by, but it weights all light evenyl between 400-700nm doesnt it(? not entirely sure), without regard for any specific wavelength that FW plants photosynthesize at a greater rate? It would be nice if manufacturers started rating light also in par though.
 
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