question about lighting

[jessinator752]

i have the 250 10k metal halide lights. i was looking on ebay to get an idea of what the price is to replace the bulbs and i see 10k 12k 14k and 20k. what is the difference? i figure the 175 250 400 ect are the watts, but i don't know what the others mean. thanks, jessica

[brewercm]

Color temp, the higher the number the more blue the color of the bulb will be but also the less PAR (amount of light the corals get which means less growth). There's much debate on what is best for the corals and how they will color up under the differnet lights. Also the same bulb may look different under a standard magnetic ballast verses a HQI or electronic ballast, usually spiking more towards the white and blue spectrum and less yellow with the HQI/electric.

[MattK]

To add to what Clif has said. 10k looks crisp white, 12k has a little blue but still looks somewhat white, 14k has a little more blue, and 20k looks mostly blue but not actinic blue. These color differences vary from brand to brand.

Here's a great article:
http://www.wetwebmedia.com/marine/setup/lighting/index.htm

[erikharrison]

the "k" stands for Kelvin. Kelvin is the relation of light color to heat. 10k is pretty much normal daylight, just standard white. It's good for fast growth, my palys and zoos have been replicating like mad under the 10k. On the opposite side of the spectrum, there is the 20k lights, which are uber blue. Anything in your tank will look like it got attacked by smurfs. It's really great for making colors "pop". Alot of people here on maast appear to like the 14k lighting, because it's in the middle. Everything still looks like its under normal daylight, and at the same time the colors still pop out really nice. I have a 10 14 and 20k set of lights which I rotate out so it's more visually appealing, as well as having a broad spectrum of light to help enhance the algae that lives in the corals!
Someone correct me if I am wrong on any of this!
Not a bad explanation for a newb, eh?

[MattK]

Someone correct me if I am wrong on any of this!
10k is pretty much normal daylight

Normal day light is somewhere between 5,000 and 6,200 degrees Kelvin.
;)

Also, the reason we use lights more towards the blue end of the spectrum is because in nature as the light passes through the water the red gets filtered out.

[jessinator752]

so i would be better off going with the 14 k then? under the 10s it seems that my corals lost some color from what they looked like under my odyssea lights on my 29 gal. my mushrooms that had a blue tint to them are now a drabby purple color and they don't open up like they did in my 29 gal. and my red mushrooms look brown and are staying really small as well. one of my two clams won't even open up since i moved them on sat. i guess i expected everything to like these lights better than my old set up. thank you everyone for explaining that to me. i had no idea what any of it meant.

[erikharrison]

Yeah the higher kelvins will help color them up. You may have some of the corals a little too close to your lighting as well. How tall is your tank?

[jessinator752]

the tank is 24 1/2 inches, the rock stands about 10 inches right now. i only have about 50 lbs in a 135 gal tank. i know i need to get more rock, i plan to this weekend. the lights are about 10 inches above the water line.

[MattK]

my mushrooms that had a blue tint to them are now a drabby purple color and they don't open up like they did in my 29 gal. and my red mushrooms look brown and are staying really small as well.

From what I have read mushrooms like the blue light.

[jessinator752]

i've heard that too, but i intend to put a little of everything in here as far as corals go. of course i won't get anything that i can't handle. i've learned the hard way to research everything before i buy it. but i'm not sure what is the best lighting which is why i'm asking people who know about it.