[paulmerz]

Hello, to start off I am in setup stage for 36g planted aquarium 30"x18"x15". I have been looking for leds and in the process of selling old reef equiptment have stumbled across a trade. My hot 250 mh for his cool 165watt 55 led fixture. Dimensions are 15.5"x8.5" specs half blue, half combination white violet green red yellow with both channels dimmable on seperate on/off switchs.


These spectrums probably won't be good for growing plants though, and who wants to look at a blue planted aquarium.. Does everyone agree? The reefkeeper said that the picture of the tank is taken with the blue channel at 100% and the other combo at 50%. He suggested if I do the reverse and take the 60° optics off the red leds I will achieve what I desire for my plants. Sounds a little sketchy but might work.

I would rather switch out most of the blues or violets for more whites and few reds and run both channels at 100%. This wouldn't be that expensive I'm willing to spend some money to make the fixture work. Although I know nothing about changing led bubs and which ones to buy. He also said they are soldiered in. How do you remove the old ones and install the new ones.

I need suggestions to determine whether making this trade is a good idea or not. Any suggestions? Help!

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[jeffkrol]

Hello, to start off I am in setup stage for 36g planted aquarium 30"x18"x15". I have been looking for leds and in the process of selling old reef equiptment have stumbled across a trade. My hot 250 mh for his cool 165watt 55 led fixture. Dimensions are 15.5"x8.5" specs half blue, half combination white violet green red yellow with both channels dimmable on seperate on/off switchs.
These spectrums probably won't be good for growing plants though, and who wants to look at a blue planted aquarium.. Does everyone agree? The reefkeeper said that the picture of the tank is taken with the blue channel at 100% and the other combo at 50%. He suggested if I do the reverse and take the 60° optics off the red leds I will achieve what I desire for my plants. Sounds a little sketchy but might work.

I would rather switch out most of the blues or violets for more whites and few reds and run both channels at 100%. This wouldn't be that expensive I'm willing to spend some money to make the fixture work. Although I know nothing about changing led bubs and which ones to buy. He also said they are soldiered in. How do you remove the old ones and install the new ones.

I need suggestions to determine whether making this trade is a good idea or not. Any suggestions? Help!

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A cool LED for a boring MH.. go for it..

As for that spectrum.. it could grow plants fine.. but as you said.. it looks blue.
The one channel alone is fine. Optics has little to do w/ it BTW.....

As to removing blues and substituting.. piece of cake or your worst nightmare depending on the board and your soldering skills..

Keep in mind that this decreass it's value to you by 1/2 (cost of new LEDs, which if properly repopulated could be anywhere from $16 to $48 based on quantity and brand.).

you pretty much have to replace an entire channel but you could leave as much as 25% blue.

A bigger problem I have is in design.. IF it is like what I have seen in others the drivers inside are practically un-replaceable.. IF it is as I suspect, they are high voltage DC constant current w/ an unknown type of dimming..

They are 2 series strings, and as such have a Vf of approx 3.2x (x) and being undivisble by 2 are an odd configuration..
now if it has a "moonlight" LED(s) that could balance it out and help Say like 3.
so now guessing at 26 LED's per string you got a 83V driver..Not easy to replace.
See this for an idea of what I'm getting at..
http://www.reefcentral.com/forums/showthread.php?t=2403985

Bottom line.. 1)you get an 80W light (only 1 channel useable, second sparingly). The color of which would be tolerable.
2)you spend another $70 (lets assume fleabay 3w) making it an excellent light or 3) you brick the thing trying to do 2

The KEY being what one channel alone looks like.. That channel alone has enough PAR for your tank. Blue is as photosynthetically active as white, if not moreso and at worst will just "compact" your growth. The other channel, except for the green is fine also. I suspect what you think is "yellow" is warm white...... but will you feel "cheated" by using only 1/2 the light..

that in mind and what you feel the MH is worth on the secondary market.. and bam decision made..

The LED sold for about $250......
http://www.bonanza.com/listings/Aqu...=&goog_pla=1&gclid=COnO1Nicj74CFagWMgodMSEAmg

Last thought.. LED's re: of type now have an inherent value higher than the MH..in some respects.. In other words a secondary trade on your part IF things don't pan out and you decide not to try to modify it..

In my head I could mod it and standardize it for like $150... but that is not cheap either..

Not sure of the longevity of the electronics, as you may note from the link I posted.. but the LED's are underdriven so no worry of failure on their part.. in general..
risk may be equal to the risk in your ballast..

Last last thought: If you have a high quality MH you are trading for a Chinese light of possibly questionable quality.. and lifespan.

 

[jeffkrol]

The reefkeeper said that the picture of the tank is taken with the blue channel at 100% and the other combo at 50%. He suggested if I do the reverse and take the 60° optics off the red leds I will achieve what I desire for my plants.

That sounds reasonable actually..but I can''t picture it not being a "cool white" color...
There are simple ways to test this theory, like white paper (keep in mind some paper has optical brighteners so the "violets" will pump a bit of fluorescence into it.) or a small collection of colored objects..

 

[jeffkrol]

Dimmer One (28 LEDs): 8x Cool White (12,000k), 6x Neutral White (7500k), 6x Warm White (3500k), 2x Red (660nm), 2x Green (520nm), 4x Violet (420nm)


- Dimmer Two (27 LEDs): 7x Royal Blue (450nm), 20x Blue (460nm)

That is your color pallet.....Ch. 2 is high PAR but relatively useless for fw uses.. i.e "look" but as a DIY.. you only have to remove 10-15 blues.. you can leave a few and RB..
You know your making me want to try..

OH one thing though.. The LED's may be not just soldered at the contacts but at their base (or thermal glue).. making removal problematic..

your "base white" in ch 1 is about 8100K.. plus the colors..so, depending on your taste.. is useable "as is" and stand alone..

 

[paulmerz]

Thanks dude, very helpful. Why will blue light compact growth? Compact growth is usually associated with higher light, correct? I actually like the look of compact growth, is it generally desirable for plant growth? Also why is green the only other color you singled out? Plants are green lol. All jokes aside thanks for your thoughts.



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[paulmerz]

That sounds reasonable actually..but I can''t picture it not being a "cool white" color...
There are simple ways to test this theory, like white paper (keep in mind some paper has optical brighteners so the "violets" will pump a bit of fluorescence into it.) or a small collection of colored objects..

What do you mean? Use a piece of paper under the lights to test the color? What would you consider cool white being 8k 10k 12k?

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[jeffkrol]

Thanks dude, very helpful. Why will blue light compact growth? Compact growth is usually associated with higher light, correct? I actually like the look of compact growth, is it generally desirable for plant growth? Also why is green the only other color you singled out? Plants are green lol. All jokes aside thanks for your thoughts.



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Generally (and apparently arguably to some) blue light compacts growth, red light stretches growth in many plants.. It is more a matter of aesthetics actually.. unless you want to eat them (differences in biomass, ect. but not worth getting into)
Green, unless you have very high light intensities, is "generally" non-photosynthetically very active.. Plants don't use much of it. Green is more of an accent color for our enjoyment..

 

[jeffkrol]

What do you mean? Use a piece of paper under the lights to test the color? What would you consider cool white being 8k 10k 12k?

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now that is a funny subject.. Some consider 6500k "cool" where others "neutral".. so it is not as clear cut as that. Complicating that is the non-linearity of the spectrum.
White LED's are inherently high in blue. it is in their design.. Blue LED w/ a yellow phosphor..creating "white" As such any LED, to my eye, is "bluish" till below 6500k but that is dependent on psychology more than reality..
But this is what I mean:

"Relative" photosynthesis (corals btw but generally applies) is the black line.. each color is a "color group" what some consider warm,neutral,coll white.. see below:

to clarify the color grouping.. You have to understand that some classifications are based on considering 3500k tungsten light "neutral" where this would make sunlight @6500k "cool white". If you set the point at "sunlight" then 3500k is "warm" light..
There is plenty of green in "whites" adding it is redundant.. AFAICT

 

[paulmerz]

Okay I got it, really I understand. Thanks for your opinion on cool white. I always thought to myself anything below crisp 10k medal halide was going to be very warm/neutral but I guess leds look cooler to our eyes at a lower Kelvin. Would you agree?

 

[jeffkrol]

Okay I got it, really I understand. Thanks for your opinion on cool white. I always thought to myself anything below crisp 10k medal halide was going to be very warm/neutral

It would be pretty neutral if you relate 10k Metal halides to "normal"..

but I guess leds look cooler to our eyes at a lower Kelvin. Would you agree?

Well to my eyes.. and it is really more subtle than that..Like 6500K It looks "white" just too white.. hard to explain..Many find it appealing and it could be mostly due to the fact I have white quartz rocks.. If I didn't have a reference white I may have never noticed..

I have a small tank w/ 7000k (and a few red leds thrown in. not many) w/ red gravel and it looks fine and neutral white.. The "too white" to me is there but not nearly as noticeable and borders on "what the heck are you talking about"..
Freshwater goes from gin clear to tannin stained to mud.. so any "white" should appear natural.
I blame it on the "dip" that you see in the white LED spectrum actually..
More silly pictures 10K MH.. no real "dips"... but weak in red (btw: do those look reversed? seems the 10k is 14k, but no matter ):

I'm just a picky old coot..
Photography is never perfect but this is an example of how I "see" things.. though not quite as extreme..

Or this:

3000K low CRI................... 3000k high CRI ....................... 6500K high cri
http://www.hkems.com/LED/eng/LED_QA.htm

for a real "geeky" approach to "white" Led's.. Now that is "white" and oddly a bit of what I went for in an LED build.. Cyan addition w/ my usual reds..

http://www.mouser.com/applications/lighting-cri/
http://www.osram-os.com/Graphics/XP...- Professional White for General Lighting.pdf
LINK for above image.. and pdf

 

[paulmerz]

Cool ^^

 

[lauraleellbp]

We need all this info in our lighting sticky- great explanations and visuals, Jeff!