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Discussion Starter · #1 ·
i went to home depot today to do a little looking around in the lighting section. i did some readings yesterday about selecting lights, and looking at the color temperatures rather than the lumen values. they (the posts) say that 5000+K is sufficient (is that true or is that not true?), so i was looking to see wat home depot had to offer.

i see that there are these 2700K 15Watt florescent. IF, per se, i used these to build a hanging hood over my 2.5G... wouldn't 15W be way too much wpg already? minding that i need 2 of them to get at least 5000+K? either way my wpg would be like 6-12wpg...

so when i do eventually go to build one, wat would i look at? K-values and wattage together, just wattage and disregard the K-values, or vice versa?
 

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K valves are a measurement of Kelvin. Kelvin is a measurement of color temperature. Example 2700K is going to be a horrible color for lighting a fish tank it is going to be a really yellow coloration and will not bring out the natural colors in fish and plants. K rating in the 6500K-10000K range going to be optimal for a planted tank. 6500K is white on slight blueish side. I have a 8000k bulb and its on the pinkish side.

If you are looking for adding things up Kelvins aren't what you want to count its either wattage or lumens. I don't know what your local home depot has but try looking for sunlight or plant grow bulbs. Walmart is a good source for bulbs as well.

WPG doesn't count for tanks smaller than 15-20 gallons as you have to have a certain threshold of light available for the plants to get any benefits. a 5 watt over a 1 gallon isn't going to grow anything and that would be 5 wpg. I would say anything under 13w is just about pointless for growing plants.

I have 25 watts over my 2.5g and I have 27 watts over my 1.5g they are don't a good job. What you are going to need to lighting will really depend on what you are planning on trying to grow in the tank and if you are going to have co2 and or adding fertilizers to the tank or not.
 

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Also.. the K values do not add up. 2700K is just yellow and two yellow bulb will give you a horribly yellow tank.
 

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wpg never counts. ever ask yourself why it breaks down on both small and large tanks? because there's no value in just looking at the wattage.

why would less area, and water require more light than a larger water volume?

shop lights aren't designed to grow plants.
 

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So what is the best K value bulb for a planted tank, 6700k or 7800k??? Sorry not to jack your thread but this should help both of us..:proud:
 

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I don't think there really is a "best". It is a matter of personal preference for most - a combination of different K-values and finding what works best for you is the best idea.

I know a lot of people use a couple 10,000K combined with a couple of lower K-val bulbs to give a good range of color for the tank.
 

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I use 6700 and 10000 combined...nice mix IMO
 

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wpg never counts.
Nice. It's always the tank is too small, too big, too oddly shaped, etc. What size of tank does the WPG rule actually work for? Who knows! 2WPG over a 100g tank is far different than 2WPG over a 10g tank. Factor in the type of lighting, efficiency of the reflectors, etc and you got yourself a mess.

I like the combination of 6700/10000k and 8700/10000k bulbs. Gives nice red highlights and keeps green plants green.
 

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Discussion Starter · #9 ·
hey mnsnowdaboy, itz alright, itz all the same topic.

so the K-values technically have nth to do with colour wavelengths that the plants can utilize for photosynthesis, but just the visual color that i can see. as for the wpg issue, thanks guys. two thumbs up =) so basically test and try and see wat makes the plant grow.

in that case, "wattage is the only thing that count and as long wattage is high enough, my plants would grow"--would this be a true statement?

but at the same time if
shop lights aren't designed to grow plants
... wat makes these 'shop lights' not grow plants when compared to 'plant' lights? and i'm gonna assume that 'shop lights' will include house lighting bulbs b/c flourescent tubes are wat they use in shops and i use them at home...
 

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wat makes these 'shop lights' not grow plants when compared to 'plant' lights? and i'm gonna assume that 'shop lights' will include house lighting bulbs b/c flourescent tubes are wat they use in shops and i use them at home...
Shop lights are designed to light up a shop, or in other words spread light over a large area. If you look at a good aquatic light reflector you'll see the light is directed DOWN to the tank, right where it needs to be. Shop lights can be used but they really aren't all that efficient and not a smart choice for a new person.

I have shop lights and they really aren't that bad. I just have too many high light plants for the shop lights to keep up with. Switching to PC this month.
 

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Discussion Starter · #11 ·
oh u mean the actually light fixture itself!! oh ya, i read about the reflectors and the efficiency issues. my real concerns are actually with the bulbs, not the reflectors. wat i thought u meant was that the bulbs they use in stores are bad, not the fixtures, haha.

but i still hope someone can tell me if wat i was thinking is rite or wrong--wattage is the only thing that count and as long wattage is high enough, my plants would grow

thanks burks =)
 

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but i still hope someone can tell me if wat i was thinking is rite or wrong--wattage is the only thing that count and as long wattage is high enough, my plants would grow
Yes, wattage IS the most important factor regarding lights for a planted tank. Of course, it is definitely not the only thing that factors into whether or not your plants grow.

Even within the aspect of lighting, there are tons of other factors that come into play about how effective your lighting is. Someone with less wattage than yourself may actually be getting more of that light into their tank thus equaling out any initial difference. K-values do matter to a certain extent. Positioning of the light matters to a certain extent (coverage). Brand of light matters. Age of lights. Some say depth of the tank relative to the amount of lighting makes a noticeable difference. That is just a few off the top of my head.

Outside of lighting, well, obviously, there are tons of other contributors that determine how your plants will or will not grow.
 
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