kelvin rating question

[billy31422]

i know that a 6500k bulb will be the best for growth. the question is. how much difference should there be in growth between 10,000k and 6500k, and does the wattage matter at all. like a 175w 6500k bulb versus a 10,000k 250w bulb. my problem is i like the color of 10,000k and i like the growth of the 6500k. any help is much appreciated

[JohnO]

I'm probably going to start a riot here, but I don't think that in general terms the Kelvin rating has much influence on growth rates of anything. Anyone have a better understanding?

John

[Birdlady]

Color temps....(or colour temps for you JohnO!) apparently do influence growth. More growth towards the yellow end of the spectrum....zooanthellae (sp?) are plants, therefore produce more food at the yellow end.

But all that takes a back seat to the PAR rating of the lamps which is related.

Here is a link that compares 250Watt MH bulbs...it gives a pic of what the light looks like and the PAR of each brand of lamp as well as the color temp...

http://metricksystem.com/chris/250wcolour/

Yellow tanks, IMO, are ugly! They look harsh and the animals will be mostly brown. That is partly why we go for the white/blue lighting , it looks nicer. Additionally, the corals tend to keep their more vibrant colors under bluer spectrums.

I have a 10K bulb, with 2 full tank length actinic tubes to soften the lighting.


Of course Watts matter. If they didn't we would all be using NO fluorescents The more watts, likely more PAR, when comparing like color bulbs. The only way to determine for certain, how good the bulb is for growth is to put a PAR meter where your corals would be. The same bulb can vary from tank to tank depending on if you have a lens cover, how close to the water is the bulb, do you clean the bulbs regularly, how deep is the tank, etc.