# 4000K PAR spotlight - any downsides?



## Desertsp (Feb 17, 2013)

I have a PAR30 (spotlight) bulb on the way and was wondering what you guys thought of it for plant growth. It's a 4000K Soraa (brand) 18.5 watt with a 60 degree lens. 

This is a high CRI bulb aimed at retail, museums, etc. Not sure exactly why I chose this one, but I figure it will look better than most of the bulbs specifically made for plants, and it has great reviews as far as making colors look natural. 

The plan is to suspend it about a foot over the center of my 18" open-topped Mr. Aqua cube, which has pressurized CO2 that I'm just now getting dialed in and the algae under control. I'd like to go for a medium level of plant mass. 

What's your take on this, specifically the overall output and spectrum? Should I consider getting a second bulb? What about supplementing with blue lights to promote compact growth? Are there any good indicators I can follow to determine if the light is appropriate once it's been installed over the tank?

Thanks!

Bump: Unfortunately I can't seem to upload an image from my iPad, but if you follow this link it has a spectrum graph on page 4. A wide peak around 630nm, and a narrower peak around 420nm. 

http://www.soraa.com/public/docs/LM79/PAR30S/SP30S-18-60D-940-03.pdf


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## jeffkrol (Jun 5, 2013)

Desertsp said:


> I have a PAR30 (spotlight) bulb on the way and was wondering what you guys thought of it for plant growth. It's a 4000K Soraa (brand) 18.5 watt with a 60 degree lens.
> 
> This is a high CRI bulb aimed at retail, museums, etc. Not sure exactly why I chose this one, but I figure it will look better than most of the bulbs specifically made for plants, and it has great reviews as far as making colors look natural.
> 
> ...


nice light.. Looks like they use a "purple" base emitter and phosphors..
The 4000k is a "tad" yellow but it will be you to decide if you like it..

Adding blue .. well at this point I'd see how it goes. Purple is like blue as far as plant response.

25gal cube and this should be enough for medium light light. It might not even look "that" way but it will be. Judge by plant response..

Consider going to about 16" from the water surface..

JUST for the sake of comparison:
Yuji high CRI bottom..
They use a UV base emitter.. but the lower K emitter is pretty similar:


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## Desertsp (Feb 17, 2013)

Thanks for the reply. 

You really think it's that powerful? 

And I would have gotten 5000K, but it's special order with the 60 degree optics. Also with all of the spillover I wanted something less harsh. But yeah I agree it might be too yellow, so it may end up being used elsewhere in the house.


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## jeffkrol (Jun 5, 2013)

Desertsp said:


> Thanks for the reply.
> 
> You really think it's that powerful?
> 
> And I would have gotten 5000K, but it's special order with the 60 degree optics. Also with all of the spillover I wanted something less harsh. But yeah I agree it might be too yellow, so it may end up being used elsewhere in the house.


I think it has a good overall spectrum, but visually to a human may not look that bright.. 
I am assuming they are fairly well made and efficient considering the target market..

Considering the more controlled directionality and better overall spectrum of the light "assuming" 1/2W - 1W t5 will give you a start on judging your light level..

In other words looks can be deceiving..











Thanks again.. A very interesting line of lighting..
My "on paper" favorite:
http://www.soraa.com/public/docs/Spec-Sheets-CC-US/Soraa SM16C 300mA.pdf


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## Desertsp (Feb 17, 2013)

I was checking out those MR16's as-well. The PAR30 will be easier to work with though, since it just plugs straight into a regular socket. 

Depending on how the PAR30 works out, I might eventually add a few MR16's on gooseneck fixtures with a dimmer for a cool sunbeam effect. 

The cool thing about his brand is that they offer snap on lenses that can control/shape the beam. Make it square, rectangular, reduce spillover, widen the angle, lower the color temperature. http://www.soraa.com/products/snap-system


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## Desertsp (Feb 17, 2013)

You were right about it being yellow. I think I'll keep looking for something with a higher color temperature. I would say it compares to late afternoon sun through a window. 

Makes the plants look great through! And lots of shimmer! 

Finnex Ray2 @ 7000k









Soraa PAR30 @ 4000K










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## jeffkrol (Jun 5, 2013)

That isn't too bad.. and actually I prefer it over the Finnex you posted.. I'm pretty sure some is a camera artifact, but it is too blue for me nevertheless..
This is cheap 3500K.. 











4000k is close to natural daylight really..


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## Desertsp (Feb 17, 2013)

I agree with you there. It's very pleasing to the eyes, but I think 5000K might be better. It really looks just like the tank is illuminated by a beam of light through an opened window. 

My tank is pretty barren right now and it just makes everything besides the plants look yellowish. I guess I need more plants 

One interesting thing is that I can finally see the different shades of green in the leaves. Under the 7000 everything was basically a uniform shade of green. 

I'll keep this thread updated as I experiment. 


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## jeffkrol (Jun 5, 2013)

Desertsp said:


> One interesting thing is that I can finally see the different shades of green in the leaves. Under the 7000 everything was basically a uniform shade of green.
> 
> I'll keep this thread updated as I experiment.
> 
> ...


mostly due to the cyan.. See the spectrum above (95CRI LED) w/ the big "hole" in the blue/green


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## Solcielo lawrencia (Dec 30, 2013)

Someone finally got a Soraa bulb. Yay! Is the 60 degree lens accurate? Is there a center spotlight or is it even? How is the color accuracy?

Digital cameras can't accurately capture violet light. Violet is essential for accurate color rendition.

I would prefer a 90 degree lens since it can be hung lower and the light will reflect off the front of the glass back into the tank. Can't really do that with a 60 due to the angle and the height.

Also, only a foot above the surface of an 18" wide tank? That's very low for a 60 degree lens. I'd double that.


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## Desertsp (Feb 17, 2013)

I'm out of town now, but I'll definitely test it out at different angles, etc next week. 

Any advice on photographing with an iPhone 6? That's all I have...

What I may end up doing is double 5000K bulbs each a few feet above and at different angles. Might even go with the narrower angles, depending on how the dispersion is with the 60 degree. Haven't had time to play with it yet 




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## Desertsp (Feb 17, 2013)

All of the standardized measurements are available in that link from my first post. I assume they're more accurate than I can achieve... On paper, it should be accurate based on the CRI. They also tested additional CRI colors which normally aren't tested. Like dark green and red. Normally a high CRI is only a guarantee that the bulb renders pastels accurately. And I really don't even know what "accurate" means in this context!

My initial impression was that it has a smooth distribution across the center of the beam, and a fairly sharp but smooth transition on the edges. I literally only had it turned on for about a minute though, and that was in a brightly lit room. 


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## jeffkrol (Jun 5, 2013)

16" above the water line is a good starting point for full top/bottom front/ back cube coverage..

you don't need more than one unless you want to play w/ shadows..or higher PAR..
You have effectively a good 28-30" (w/ substrate) distance. light to dirt. Which is really only 1 meter ish..
1M = 39.36"

According to the table that is 1700-ish LUX in the center 12"

Crude conversion of Lux to PAR
http://www.apogeeinstruments.com/conversion-ppf-to-lux/

Lux x .015 =25.5 PAR at the floor in a 12" radius @ 1M

Since "my" recommended height is only 30 not 39.36" you get a rough Par increase of 25%...32PAR at the substrate..Not quite sure on the field but roughly around a 10" circle..


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## Desertsp (Feb 17, 2013)

Interesting. Amazing how powerful this little bulb is...

Tonight I'll rig up the light at your recommended height and see how it works. May also take some photos of it against a wall to visualize the distribution. Assuming it must be fairly uniform given that one of the advertised applications is illuminating artwork, but if not, that could play into a decision whether to use one or two bulbs. At this point nothing is set in stone, and I'm probably going to be switching to 5000K anyways so I could easily order two more bulbs. Or maybe have one 5000K and one 4000K?

In nature, the sunlight varies by angle and intensity throughout the day, is there any concensus as to whether simulating such an effect makes a difference with planted aquariums? 

The thing I love about this hobby is how you can overcomplicated things as much as you want, lol.


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## Desertsp (Feb 17, 2013)

jeffkrol said:


> According to the table that is 1700-ish LUX in the center 12"


Is this derived from the 1129 central beam candle power?


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## jeffkrol (Jun 5, 2013)

Desertsp said:


> Is this derived from the 1129 central beam candle power?


no Lux chart pg10 (or 11)
http://www.soraa.com/public/docs/LM79/PAR30S/SP30S-18-60D-940-03.pdf


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## Desertsp (Feb 17, 2013)

Missed that...

So here's how it looks 12" above the surface. Will try 18" tomorrow, but I need to find a sturdy riser for the lamp first. It's quite a bit more yellow in real life. 










About 30" from the wall:


















The way the branches cast shadows, I think I'll need a second light for more even coverage. It's a very narrow point source, most of the light seems to emit from the center 1 inch of the lens. 

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## Desertsp (Feb 17, 2013)

The plastic lens is removable with a few Phillips screws.

























Without the lens.










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## Desertsp (Feb 17, 2013)

Comparison of 5000K (left) and 4000K, in case anyone's interested. 

Decided to stick with the 4000K as I've gotten used to the slightly 'yellow' cast and it actually makes the fish and plants look much more vibrant than the 5000K bulbs. 




















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## Xiaozhuang (Feb 15, 2012)

I find the 4000k perfect actually, not sure about the trend towards very cool/bluish light in planted tanks


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## Solcielo lawrencia (Dec 30, 2013)

The perception of color temperature is highly dependent upon relativity to other light. 5000K is not blue at all but appears so next to lower K light.

Also, the camera had to make a choice as to which light was considered "white" in the side by side picture. It obviously WB'd to the 5000K. A better comparison can be made by taking a picture of real objects, not a wall, and compare color reflectance.


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## Desertsp (Feb 17, 2013)

Yes, it's a pretty unscientific demonstration of the differences. This is close to how it looks in real life though, at least to my eyes. 

The wall itself is not white either. 


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