# Too Much Light?



## hcubed (Sep 3, 2010)

There is so much already written about lighting here that I hesitate to start a new post, but after reading a lot of the threads, I can't find a specific one that seems to address my problem.

Most people talking about lighting seem to be after just the right combination of light quality (spectrum, Kelvin temp rating) and quantity. It seems a lot of folks are trying to get as much light as possible. I'm wondering if I just haven't come across the right blend of spectrum or if I'm an oddball and prefer a dim aquarium.

I started with a decade old Perfecto hood with double T-12 48" bulbs. They weren't rated but still had "Pefecto" on them. Is it possible they are the originals? Either way, they are OLD. I quickly discovered one ballast was bad, so only one T-12 bulb would light (I'm sure with much less intensity than a new one). I replaced it with a new T-12 bulb from Lowe's I had in the house rated 5,000K. Even though it was still only one bulb, it seemed too bright, too yellow, or both.

I decided instead of messing with fixing the ancient fixture with a bad ballast, it was time to get a new one. I didn't have time for DIY, so I got the identical Perfecto double 48" strip light fixture, except this has electronic ballasts and takes T-8 and T-12. It just arrived. The included T-8 "daylight" bulbs don't have a K rating, so I have to assume they're around 6500K. I had hoped new daylight bulbs would make everything look great.

It seems too bright and too yellowy to me. Oddly enough, the best of what few options I've tried so far seems to be ONE ancient Perfecto T-12 bulb with an unknown K rating. (BTW, I've read about actinic but don't want to spend the cash without knowing if I'll like them. I really don't want everything in my aquarium to have a blue tint. I just want the brown wood to look brown, the golden sand to look golden, the red and earth-tone rocks to look their natural colors.)

Am I just weird and like a dim aquarium, or are 5,000K and 6,500K just not the temperatures for me?


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## Andras (Jul 17, 2010)

Something around 10000k would be more of a white light. The higher the k ratings the less yellow the lights should look. I do stress should because I have seen two bulbs with the same "daylight" 6700k ratings from two different manufacturers, and one looked yellow compared to the other.


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## Number6 (Mar 13, 2003)

*hcubed*
the greener the bulb, the brighter it looks to the human eye... so anything in between 4100K and 7000K will be "bright". Bulbs also have a burn in period so it'll be brightest when new...

I really like dim lights over my Tanganyikan fish and I love the deep water look of broken up lights on the bottom of a tang tank. I switched to cheap white christmas lights and love it... uses no power worth worrying about!


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## PfunMo (Jul 30, 2009)

Something that we sometimes overlook is how the ratings are done and what they mean. Being rated at 6500 doesn't mean it puts out 6500 only. The coatings on bulbs is what sets up what light comes out and it doesn't all come out the same. A 6500 rated bulb will have other wavelengths as well scattered in. Often some higher and some lower. It works somewhat the same way radio waves work. When a transmitter is set to a frequency it will also put out radiation on either side of that frequency. The difference is that the radio parts can be designed to kill off those other freqs. In a bulb we can't do that very well so they just shoot for a frequency and live with the rest. The rating is a kinda/sorta average. In fact, on any given day the light put out by a bulb may vary slightly due to the different power it is receiving. Makes for a pretty messy decision sometimes. It's actually really good that our eyes don't see very well the things that go on .


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## hcubed (Sep 3, 2010)

It's not technically the brightness I have a problem with, so much as the coloring of the light. If the browns looked brown, golds looked gold,each color looked like it should, I'd be happy. So far it seems 6500K and under isn't to my liking even though it's supposed to have the "full" spectrum of light--things still look all the same washed out greenish-yellow. I'm worried an actinic will make everything look blue. Maybe I need to keep trying on up the K scale... 7,000KÃ¢â‚¬â€œ10,000K. Maybe I'd actually be happier using only one of the two bulbs. Whatever the solution, I need to keep enough light for anubias and java fern to grow.


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## BillD (May 17, 2005)

If you want things to look natural, you need to look at the Color Rendition Index. CRI. The higher the number the more natural the color rendition. Sunlight has a CRI of 100, to put it in perspective.Generally, 5000K lights have the highest CRI, although that isn't necessarily true. Case in point, Philips Natural Sunshine, in T12 has CRI of 92, While a T12 Ultra daylight is around 84. Clearly, this is a significant difference. If you look at the same tubes in T8, the Natural Sunshine 5000K, has a CRI of 84, While the T8 Ultra Daylight has a CRI of 85. For whatever reason, the CRI did not translate well in the downsize from T12 to T8 for the 5000K tube. I use both color temps, and probably prefer the 5000K tube, but the 6500K Daylight tube is definitely whiter/bluer.


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## blusue2 (Sep 9, 2010)

What color is your background? I've found that the whole tank changes its coloration depending on the background--even with the same lights.


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## hcubed (Sep 3, 2010)

Background is black aquarium paper. I have a photo of my aquarium decor (with no fish because I'm cycling) in My Tanks, except I think it's still the dark blue aquarium paper. Changing to black didn't help the yellowish-green tint I see in everything.


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## Number6 (Mar 13, 2003)

*hcubed*
billd is bang on... you want a crisp white to blue light with a very high CRI. You might have better luck finding that in the higher end reef lamps like actinic white than your run of the mill pet shop lamps.


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## hcubed (Sep 3, 2010)

So it sounds like it's NOT just Kelvin rating after all. It's Kelvin rating and CRI?

1. It's not proving easy to find CRI ratings, even for specialty aquarium bulbs.
2. It's not proving easy to find WHITE actinic 32W T8 bulbs.
3. So I want a high CRI? What qualifies as a "high" CRI in my case?


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## Glaneon (Sep 27, 2010)

I would hazard that the CRI of 100 = sunlight (our common reference).
the closer the number to that, the more accurate the colors will be.

Will that be what you want? I dunno.

I tried quite a few different temps (what you were looking for too) and found I like the 10k bulb, but what I have is a Power-compact... but I will be in your boat this weekend I think.

Tank lid I just bought used has a blue actinic which will look blah over my malawi cichlids.


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## BillD (May 17, 2005)

I would hazard a guess that it will be difficult to beat the CRI of 85 on the Philips Ultra Daylight that sells for $4 at Home Depot. i don't have a problem with the tubes I'm using with colour rendition. Everything looks okay to me. My planted tanks are using a tube with 5000K and CRI of 82.


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## hcubed (Sep 3, 2010)

I ended up going with one Zoo Med 10,000 K fluorescent ($27) and one cheap daylight bulb from a big hardware store. The two together work well to my eyes. I hated spending that kind of money on the 10,000 K bulb, but not as much as I hated looking at a yellowish tank all the time.

Also, the new $100 Perfecto double-strip light was warped and didn't sit perfectly flat. I returned it and replaced the OLD ballasts in my old Perfecto hood with one new electronic ballast that cost $12. Quite easy to do, actually.

HCubed


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