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06-27-2019, 11:23 PM
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Senior Member
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Join Date: Jan 2017
Zone: 6b
Location: New England
Posts: 139
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Counterbalancing Cold Color Temperature (K) in LED lights
Hello All,
I recently expanded my space for my orchid collection, and I now have orchids in a windowsill in my kitchen. I purchased an aquarium plant light.
Here's the light I purchased:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Now, I know that aquarium lights usually aren't bright enough or aren't the right color temperature. The specifications online indicate that the light produces 4800 lumens and has 6500k white lights WITH added blue lights. I decided to get this less than ideal light since I need something that is powerful yet compact enough to fit in my windowsill. My windowsill does get some nice light during the day but it's probably not enough for phalaenopsis to grow.
Now, I knew that the light might have a bluish tint because of the already cold(er) 6500k lights and added blue lights. When I plugged the light in, my suspicions were correct. The light appears to have more of a 7000k (maybe 7500K) color temperature. To counter-balance this, I thought to get some LED tape that has a warm color temperature or is red in color. I'd just stick the LED tape to the existing light. Here's what I got:
Commercial Electric 12 in. (30 cm) Linkable RGBW Indoor LED Flexible Tape Light Kit (4-Strip Pack)-17898 - The Home Depot
The white lights are 4000K color temperature. It doesn't indicate lumens for the white light colored option. When I plugged in the light it isn't as bright as the aquarium fixture and it doesn't do much to counterbalance the cold color. When I use the white lights it does add a bit more brightness (about 200fc). It doesn't visually appear to counterbalance the cold color temperature. The red light option isn't nearly bright enough to observe a difference. Therefore, I suspect it is useless.
Long story short, my question here is: Is the natural sunlight I get from my window enough to counterbalance the cool color from my LED lights? If not, despite a negligible visual difference in color temperature with the light strips shining red, are they still beneficial? Perhaps the naked eye cannot observe the difference that may be beneficial? OR am I fine doing nothing at all?
Thanks for reading everything! I appreciate your help.
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02-27-2020, 08:38 PM
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Member
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Join Date: Jan 2019
Zone: 7a
Location: Langhorne, PA
Posts: 36
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This is a tough one to unravel. I don't want to discourage you, but neither of these lights are appropriate for growing orchids. There are two major concerns when choosing a grow light - irradiance, and photosynthetically useful light. You really want to know the PPFD (particle photon flux density) output of your lights so you can decide whether or not you have sufficient light, then dial in how far away to place the lights. Without that figure, we're just ball-parking. The other concern, photosynthetically useful light, can be explained with a spectrograph. There are a lot of articles that go in depth. PPFD, Daily Light Integral, and the spectrograph are key. If you're looking for well balanced light output, consider blurple lights. White LEDs dont actually exist (they're yellow with blue powder coating), so they're less efficient overall. Even if though hit all the colors on the spectrum, they offer less useful light.
Here are my recommendations (either of these can come in blurple or white, but check out the spectrograph in the first listing, it illustrates blurple vs white):
https://www.amazon.com/dp/B07MV2GF84...p_mob_ap_share
https://www.amazon.com/dp/B07FZTKYXV...p_mob_ap_share
All this being said, Phalaenopsis are low light plants and hardly ever need supplemental lighting. East windows are great, near but not in a south or west window works. North windows are insufficient.
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02-27-2020, 09:35 PM
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Senior Member
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Join Date: May 2005
Location: Oak Island NC
Posts: 15,159
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Sorry, but I'm going to have to disagree to some extent with the response above.
While not ideal, the light you have and the one being considered are adequate. There is nothing wrong with "ballparking" it.
Don't be too swayed by the color temperature, as in both fluorescents and LEDs, it is not a true reflection of the spectrum, but is an indication that it looks like "that" true color temperature to the human eye.
Yes, PPFD, DLI and spectrum are important if you're trying to be super efficient or are someone shooting for the ideal conditions, but our plants have been grown for years without that info, so they are anything but necessary. Would it be wonderful to have that info - of course!
Plants need a range of total photon flux during a day, which varies from plant to plant. That means it needs "so many" photons over the PAR range of wavelengths. Again, having the spectrum match that of the sun is ideal, but unless it's really narrow and/or skewed to one end of that spectral range or another with a white light, the total received plays a bigger role than does the spectral details.
White LEDs are not yellow with a blue powder coating. They are typically blue or UV chips upon which a fluorescing phosphor coating has been applied, making them a solid-state analog of a fluorescent bulb. With the proper phosphor blend, the output spectrum can be tuned to emit an excellent spectrum for plants, but lacking that, most white LEDs are adequate, if they emit enough photons, and those with "warmer color temperatures" tend to emit more far red, which is supposed to be a "plus" for blooming.
And when it comes to phals in windows, since moving out of a greenhouse in southeastern PA, mine have been facing north for 3 years and are doing beautifully. Yes, they took some time to adjust to the lower intensity, but they are deep shade plants, after all.
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02-28-2020, 04:21 AM
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Senior Member
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Join Date: Jul 2013
Zone: 6b
Location: PA coal country
Posts: 3,382
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Define "aquarium lights"! I used to own an aquarium maintenance company, and frequently got old light fixtures when customers upgraded or took down their tanks. My winter setups still consist of lights acquired that way. Lights intended for reef aquaria can be every bit as bright as an purpose built grow light, as can lights intended for freshwater planted aquaria. My main set up is a 4' x 2' shelf unit lit by 2 ancient Taotronics 120W LED black box units suspended high enough to allow a mature Cymbidium to fit underneath. I've bloomed Cymbidium, Vanda, and high light Cattleya such as C. aclandiae under them. They're heavily skewed towards the blue end of the spectrum with a combination of 10,000°K white and 20,000°K blue emitters. I also have a smaller shelf unit lit by LED strips intended for planted aquaria that I keep and bloom Cattleya under.
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