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I'm planning on getting a 18,000k bulb for my 29g, and I was wondering if it would have any negative effects on the tank (excessive algae growth, burning fishes' eyes out, etc).

Anybody have any experience with these bulbs?

i bought one at the lps a couple days ago but bought a t-10 when i needed a t-8 . just keep an eye on your fish to make sure they are ok with it. they will all hide if they think the light is too bright [/font]

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"That's the trouble with political jokes in this country... they get elected!" -- Dave Lippman

Hi,
Actually this has been the subject of much debate on
this, and other forums. Plants prefer spikes in the
red and blue portion of the spectrum. Bulbs in the
10,000K range and up are primarly blue. The light
from these bulbs penetrate deeper into the water.
Bulbs that are lower in K temperature, loose their
effect within a few feet of water.

Salt water tanks, especially those with corals
and other inverts, use lights that start at 10,000K
and go up. The inverts use this light to create
chemicals that color them, and chemicals they
consume. Without this light, they would die.

Lights that are that high in K temperature generally
give a washed out, bluish tinge, to plants and to the
human eye, that changes our perception of their greens.

Overall, the best (IMO) bulbs are those that have some
of each, the red and blue, parts of the spectrum that
plants want. Bulbs that run around 6700K generally
allow us to preceive plants in their "true" colors,
and shades of greens and reds.

Unless your tank is deeper than 18 inches, switching
to an 18,000K bulb makes no sense. Changing K ratings
of bulbs is not a way to increase the Watts/gallon
rule of thumb.


Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

It's on a 29g tank (bit more than 18" tall, but the distance from the gravel to the light is about 16"-17'), so I kinda need light that goes down deeper into the tank (especially with baby Elodea).

I'll get one and see how it goes. Thanks

10,000k is as high as I would go on a 29 gallon, but even then the 10000k looks a little too bright for me.

Personally I think you&#8217;ll be wasting you money with the 18000K bulb. As the others have mentioned it&#8217;s a bulb meant for use in SW aquariums with coral.

Yes it may succeed at getting light to the bottom but at a cost. The light is just way too blue, which is of more use to algae then plants. But the biggest drawback is that visually you will probably hate the look of the tank. Plants colors won&#8217;t come thru and they&#8217;ll just &#8220;look&#8221; sickly, it will also wash out the fish colors making them look very pale. When I bought my light fixture it already had 12000K bulbs installed which I thought I&#8217;d try (I have a very deep &#8220;show tank&#8221 but I just couldn&#8217;t stand the look, horrible. After about 2 weeks I couldn&#8217;t stand it and I changed over to 10,000K and it was like I had a new tank, everything suddenly had color !

Really I wouldn&#8217;t go above 10,000k and as your tank is not that deep at all 6,500K should be fine. As Frank stated spectrum cannot make up for a lack of intensity. If you think the light is not sufficient for your ground cover plants increasing the number of bulbs is the only option, 18,000k bulbs won&#8217;t improve the situation and will only give you a new set of problems to deal with.

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Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.

I'll get a 10,000k bulb then...

Thanks for the help

I love the blue light on my 55g. The congo tetras look much better and are more active. The yellow is now an irredescent green/blue, the red shows up great and their blue is neon blue. The fins are now tipped with blue as well. My crypts are sending out new plants, the lillies have grown half way up the tank, and the apongeton must have spread seeds or whatever it does because my tank has little apongeton sprouts all over. Much better than yellowish or even pure white light.