K and Lumens

[cbong]

Just bought a 1 feet PL light holder from NA. Comes with 2 x 9W PL tubes. Wanted to change it to a higher Wattage. Went round and found 11W & 13W types, but could not find the value of the K. Looking for a 6500K range but some indicate measurements as Lumens instead.

Is there a conversation between K and Lumens? Any relationship?
If there are no indications of K, any other ways to determine that it is suitable for planted tanks?

Your advice pls, thanks

[hwchoy]

K refers to the temperature of the "black body" (remember blackbody radiation? because I only have a very vague recollection by now ) basically it tells you the colour of the light produced.

Lumens refers to the luminosity or intensity of the light.

You should look for somewhere around 6500K or "daylight" or "cool white". Lumens should be higher the better.

[Aeon]

9W PL lamps usually come in 600 lumens.
7000 - 8000K is what I like...

You can look at the Model of the lamp and tell what K is it...

like G23865 and ABC67 are 6500 and 6700K respectively... no gaurantee though... cool lamps usually have blue or green colors on the box and orange for warm lamps.[/u]

[neon]

[quote:08c9e74da0="Aeon"]9W PL lamps usually come in 600 lumens.
7000 - 8000K is what I like...

You can look at the Model of the lamp and tell what K is it...

like G23865 and ABC67 are 6500 and 6700K respectively... no gaurantee though... cool lamps usually have blue or green colors on the box and orange for warm lamps.[/u][/quote:08c9e74da0]

Hi ,

I am using the Osram 150W MH, and the spec is 11000K. I know I should be using 6500K for the planted tank. Except this bulb is very much cheaper than the other MH bulb from the LFS like arcadia.

It will suit the marine tank, struggle a bit the green algae on the front side glass, other than that not much issue on the plant.

Does this intensity promote green water ? Or is it the water condition not good yet , require right dosing regime ?

please advise.

[Aeon]

[quote:0cbb8f225b="neon"][quote:0cbb8f225b="Aeon"]9W PL lamps usually come in 600 lumens.
7000 - 8000K is what I like...

You can look at the Model of the lamp and tell what K is it...

like G23865 and ABC67 are 6500 and 6700K respectively... no gaurantee though... cool lamps usually have blue or green colors on the box and orange for warm lamps.[/u][/quote:0cbb8f225b]

Hi ,

I am using the Osram 150W MH, and the spec is 11000K. I know I should be using 6500K for the planted tank. Except this bulb is very much cheaper than the other MH bulb from the LFS like arcadia.

It will suit the marine tank, struggle a bit the green algae on the front side glass, other than that not much issue on the plant.

Does this intensity promote green water ? Or is it the water condition not good yet , require right dosing regime ?

please advise.[/quote:0cbb8f225b]

There's no hard rule that 6500K should be used. Amano uses 8000K and some swear by 9325K and some have fantastic results with 6500K. It's more of the quality of the light which is determined by the spectrums which it provides for the plants and in what intensity (lumens) + other factors. The K rating is just the color temperature, and not the spectrum. cool lamps does not contain more blue, it appears blue.

Almost all high light tanks will have green algae on the glass. It is more of an imbalance of nutients and water conditions, lighting, CO2... than lighting alone that causes algal infections.

[kelloggs]

Just want to check with the experts here. My tank is 90 gallon. I am using 4 x 36W PL (8000k) and 4 x 36W PL (6000k). Saw someone mentioned that at least 6500k is sufficient. Shall i change the set of PL which is only 6000k??

[vinz]

Nope, 6000K is ok.

K is not about the amount of light, but the COLOUR of the light. Human eye are tuned to seeing things rendered by daylight (sunlight), hence daylight rated lights make our tank colours look more "natural". In quotes because, this is as perceived by the human eye.

You cannot use K as a guage of brightness. For example, some animals do not see the red light very well. In a room with just a red lamp on, it will appear to be very dim or totally dark to these animals. One of the tricks (I read) to catching escaped caged birds, is to completely darken the room then use a red torch light to find and catch the bird.

[Aeon]

The CRI (Color Rendering Index) property of a lamp plays a more vital role than K in rendering natural colors. A high CRI (>90) shows natural colors, regardless of color temp. But normally higher K rated lamps will have higher CRI. I still feel 6500K lamps are yellowish... by the way when you look at the sun in midday, it's yellowish too. So I like to use 8000K because it appears more whitish.