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Do all bulbs with the 6500k rating make your tanks look green?

This is a discussion on Do all bulbs with the 6500k rating make your tanks look green? within the Beginner Planted Aquarium forums, part of the Beginner Freshwater Aquarium category; --> 6500K gives you the most bang for your buck (or, bang for your wattage) If you have plentiful light, then less-than-ideal color temperature should ...

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Do all bulbs with the 6500k rating make your tanks look green?
Old 03-10-2012, 05:07 PM   #11
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6500K gives you the most bang for your buck (or, bang for your wattage)

If you have plentiful light, then less-than-ideal color temperature should balance out... Might get algae, might not. Worth a try though.
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Old 03-10-2012, 08:02 PM   #12
Originally Posted by redchigh View Post
6500K gives you the most bang for your buck (or, bang for your wattage)

If you have plentiful light, then less-than-ideal color temperature should balance out... Might get algae, might not. Worth a try though.
I disagree with this. Kelvin temp means very little its the color spectrum that matters. I've seen 6500K tubes with 'less-than-ldeal' spectrums compared to higher tubes.

Drs. foster and smith give this as the Life glo 2's spectrum. We know plants like red and blue light and can not use much of green light. I simply would not use these tubes due to the huge green/yellow spike, which I view that as wasted light. Not all 6500K bulbs are the same as color temp has little to do with spectrum.

Below is the spectrum for the GE 9325K bulbs I use. I absolutely love these bulbs. They give great color with none of the green look.

In comparison this is the standard all-glass 8000K tube which has a surprisingly nice spectrum IMO for plants. Things may look off-color due to the lack of green but plants are only green because they reflect green light. They can't use green light so I personally avoid buying any premium cost bulb that has a really strong green peak. With very little green though the tubes tend to have a pinkish color, which some people like and some people hate.

When it comes to cheap bulbs like 6500K CFLs there is no spectral data. Some do look very green while others are more white. I prefer to stick with the white ones. Avoid 5500K 'daylight' ones.....

Bulb colors can be tricky and more noticeable in some situations then others. Below is on of my soil based tanks shot from one of the ends. In the back of the tank there are 2 6500K CFLs and in the front there is a 9325K bulb. Side by side they look very different, especially the color of the sand. The higher bulb definitely has a pink hue to it both grow plants just as well for me.

My main high tech tank uses just the 9325K bulbs and it looks like any normal tank, the pink is not noticeable and I would assume that is due to the dark substrate.
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Old 03-10-2012, 08:30 PM   #13
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Great info!
I use two 6500K bulbs on my 25g, which is clear water. And I use one 6500K each on my 3g and 10g. All tanks look just fine, and the plants seem to like it. And the bulbs are pretty cheap! win-win-win!

But for the 55g blackwater...
Where does one purchase "GE 9325K bulbs"? The strong orange spike is appealing for blackwater use. It sounds like these might work well for me, and the OP, too! But I can't remember seeing these for sale anywhere. (I'm in Ohio, in the states, if that matters.) Thanks!
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Old 03-10-2012, 11:18 PM   #14
For the GE the main ones I use are 55 watt power compacts so I generally have to order them online as no store carries those kinda bulbs at a decent price lol.

I found a 15 watt T8 bulb at walmart, but I don't know if thats a regularly carried item. It was in the fish section though.
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Old 03-11-2012, 03:46 AM   #15
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I don't run PCs. As far as I can tell, the don't make the 9375K in a 48" T8 bulb.

I'm looking around, but I'm having trouble finding a T8 that looks like it might work, and then imagining what the spectral chart translates to in reality.

Would either of these work?


But then I can't find the K on them...
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Old 03-11-2012, 11:44 AM   #16
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What has been posted about spectrum and kelvin is quite correct. The spectrum is significant for plant growth response, while the kelvin (generally) determines the appearance. But the contents of the aquarium also play into this.

Three weeks ago I did a major overhaul on my 33g, which had become overrun with plants. This tank has a single T8 Life-Glo over it. It sits between my two largest tanks that have the same tube as one tube plus a Phillips 6500K daylight as the second tube. Normally, the three tanks look much the same with respect to the colour hue. After I did the major pruning the 33g was quite incredibly more cool bluish white for days. I did not change any tubes. Clearly, this was due to the removal of plants and the major water change (about 75% of the tank) which removed the "old" water. Now, after 3 weeks, it is basically looking the same as the two on either side. Point here is that the water, what's suspended in it (particles reflect and absorb light), as well as the plants themselves can affect the hue.

If you have a dual tube tank you can achieve a good combo. I prefer a full spectrum or daylight tube such as the Life-Glo as one tube, combined with a much cooler more-blue than red tube with a K up around 9000-11000K. The stores around me no longer carry the latter, so for the time being I've gone with Life-Glo plus Phillips daylight deluxe, and it is a warmer (more yellow/green) hue.

The Life-Glo at 6700K is not as "warm" as the 6500K cheaper tubes. I can see a distinct difference not only in the tank but in the tubes themselves lit side by side in the fixture.

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Old 03-11-2012, 11:11 PM   #17
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I buy whats cheap. Even the spiral CFLs for my 20 long only runs me about 15 bucks to swap all 3 bulbs out. The only bulbs that cost me money are the ones for my 55g because no hardware store carries full spectrum 24" T8s (god only knows why). I have lots of problems with my plants, my lights have never been one of them. To each his own, but its my feeling that finding the perfect bulb with the perfect spectrum is a bit like splitting hairs (or splitting hares... ew ).

just my $0.02. If its an aesthetic choice, do what you must. I dont have to look at it, you do!
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Old 03-12-2012, 01:14 PM   #18
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Here are two photo's of the same exact tank taken about a week apart, the only difference is the bulbs everything else is exactly the same. (sorry about the one being blurry, stupid phone camera, and excuse the plant mess, I was neglecting the scape while setting up my reef, she's all cleaned up now)

Anywho, one is a photo while running the Aqueon 8000k the other while running a Life-Glo 6700k. The 8000k emits more of a purple light (not nearly as bad as the "plant bulbs" do though but noticeable by looking at the reflection from the black background) Comparing the spectrum you can see why. The Aqueon is high in the Red/Blue spectrum but lower in the yellow/green while the Life-Glo peaks in the yellow/green. Makes sense.

I "tested" (after a few too many beers mind you) the lights with a white sheet of paper on the floor of a dark room. I in no way expected accurate scientific results, just wanted to see if there was a large difference between the two. To the (drunken) naked eye in a totally dark room the Aqueon emitted a less intense "dull purple" light onto the paper and was slightly below the Life-Glo in intensity (room was less bright). The Life-Glo bulb on the white paper was nearly pure white, not too much yellow and seemed to light up the room better. Could just be from the extra 3 watts though.

Most of the yellow/green you are seeing in your water is going to be either from the tannins/plants/decor reflecting more green/yellow light.

Now that's all good for "explaining" the visible color rendition of the bulbs to the naked eye. The ability for these two specific bulbs to support plant life was heavily discussed by Byron, Quantum, and myself in this thread The Aqueon in theory should be better for plants as it peaks in the red/blue... but... there are many many other variables other than spectrum alone that come into play.

I've personally used both bulbs and from my non-scientific observations in plant growth (comparing pictures over set amounts of time) the advantage very slightly goes to the Life-Glo (even though it's peak in the spectrum isn't as high in the blue/red areas). The vast change in appearance did take some getting used to though (wife likes the bright green better, mostly because it offsets/contrasts the enormous amount of blues/purples emitting from the reef tank 10ft away) I personally kind of liked the color of the Aqueon bulb, seemed as though it gave it a more natural color rather than the lime green from the Life-Glo. Either way though as I said the growth has been nearly comparable, with a very slight lean towards the Life-Glo which again could of been due to many other variables.

So since either one WILL support plant growth and rather comparably I'd say go with what you like the look of better.

Aqueon 8000k spectrum

Aqueon 8000k Photo

Hagen Life-Glo Spectrum

Hagen Life-Glo Photo
(sorry about the blurry photo, just to show color rendition)

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Old 03-12-2012, 03:57 PM   #19
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I would much rather sit in front of the tank lit as in the second photo as opposed to the first. The colour rendition of plants and fish is true under Life-Glo. It is not under the Aqueon. I'm not going to rehash all that was in that thread kangy linked, but I will throw out a few facts.

First, intensity. The Life-Glo is more intense light than the Aqueon, so your (kangy) perception of brightness is not off the mark. All of the red/blue tubes I have ever tried were about half the light intensity of the full spectrum.

Back to the colour rendition. The Life-Glo (and similar spectrum tubes) is about the closest to mid-day sun that there is. This is why one can say that the colour rendition of fish and plants is true.

I am not going to start throwing names around, but every knowledgeable planted tank author I have come across does give full spectrum tubes with a kelvin around 6500K to be the best for natural planted aquaria. The scientific study cited in Walstad that redchigh mentioned in that linked thread proved the same. Plants definitely grew "better" under cool full spectrum light, having a kelvin from 6000K to 7000K.

With sufficient intensity, plants will normally grow fine under any light, not too extreme. But the studies have indicated that they grow easier or stronger within that specific range. I'm not aware of any studies that contradict those, so I tend to accept them.

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Old 03-12-2012, 06:00 PM   #20
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Just today I changed the strip light on my 10g from a single tube to dual 10 watt CFLs... went from 9000k to 6000k CFLs. It does look a bit more "green" but definitely a bit cooler. Unfortunately I didnt take before pictures, but it looks 100 times more natural.
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