converting sauna --8 bulb T5 HO --too much?

[dshallpost]

Thank you Estacion. I didn't know that the T5HO would generate heat. May-be I should look at LED. Also, I have two "benches" one about 36 inches wide and one about 18 inches wide, both about 5.5 feet. I was going to use an 8-lamp and a 4 lamp. May-be I should dial that back to a 6 lamp and a 2 lamp. Would appreciate any input. The 36 inch wide bench is actually 18 on two levels (which can be adjusted) to get various distances from the lights. I don't want to have too much light for the space.

[estación seca]

There are lots of threads here on Orchid Board in the Growing Under Lights forum.

If I were starting from scratch with lights I would unquestionably buy LED. Those of us with legacy equipment, who either don't use lights much, or don't have money for converting a lot of fixtures, are remaining with our older technology, but converting bit by bit.

Other people are much more familiar with LED than I am. I would listen to their recommendations. A few things to keep in mind:

People use the word "fixture" to refer to the whole assemblage, including the electric cord, electronics inside, housing, and the part that emits the light. People use the word "lamp" to refer to the thing emitting the light.

Conversion from electricity to light in a lighting fixture will always release heat. Higher-efficiency technologies convert more electricity to light than do low-efficiency technology. LED fixtures can be much more efficient than any other kind of technology available. Incandescent technologies, including high-pressure sodium lamps, release the most heat per amount of light.

Incandescent lamps release large amounts of heat, together with light, from the filament. The heat is right there with the bulb. These are good for warm-loving plants, but can be a problem in many situations. Some incandescent lamps can severely burn human skin in less than reaction time.

Fluorescent lamps of all technologies release some heat together with the light. Old fluorescent lamps are quite warm to the touch, but there is plenty of time to withdraw the hand before burning. CFLs are less warm but still may cause burns with a few seconds' exposure. High-output T5 fluorescent lamps are hot enough to burn at a touch.

LED lamps (or "emitters") do not release much heat. They can be worn around the neck as decorative jewelry.

LED, high-voltage incandescent and the various flavors of fluorescent fixtures release heat at the transformer and power inverter, which may not be immediately adjacent to the lamp. If you can have a fixture with the lamps away from your plants this may be a plus.

More efficient lamps release more light than less efficient lamps with the same electricity input. But some LED lamps release more light at wavelengths plants can use than do other LED lamps with the same electrical efficiency. The measurement is PAR, photosynthetically active radiation. You will be looking for something with a higher PAR value.

[dshallpost]

Thanks for your guidance. I would love to have reactions to this fixture that I am considering. You can see it on the HydroFarm site. It is called the PowerPAR Commercial PPL4. It is LED. It has 16000 initial lumens, 120 lumens/watt. It is 6500K. No idea what the spectrum or CRI is. It is about 4 Feet long. What do you think?

[estación seca]

I don't know enough to answer. I'm responding to say color temperature in K has no relevance to growing plants. It is a measure of how the light emitted from a particular lamp looks to a human eye. Plants and human eyes respond to light very differently.

Color temperature in degrees K might matter in terms of how plants under the light appear to viewers. Some LED fixtures emit only pink and blue light intended to match chlorophyll absorption peaks. These look awful to most people.

By happy coincidence the relatively inexpensive combination of phosophors in fluorescent lamps with a color temperature of around 6000K emit light that is very good for growing plants. So people began thinking 6000K or 5500K or 6500K light is best for plants. That is only true for some fluorescent lamps.

Other light technologies will use different methods and different combinations of light wavelengths to get a pleasing look to the human eye, so those color temperatures in different kinds of lamps will not necessarily mean those lamps are ideal for plants.

My observation has been a lot of people don't understand this about color temperature, and focus on color temperature when selecting lamps, ignoring things that actually make a difference. Vendors report color temperature mainly because people mistakenly think they need to get 6000K for their plants to be happy.

I would look for a nearby hydroponics shop, talk to the staff and ask questions about light fixtures. Many people who shop at hydroponics shops grow crops much more valuable than orchids, and they pay attention to what works best. If I decide to get into light growing in a bigger way I'm going to do that.

And continue reading here on Orchid Board. There is a lot of technical information on lights. For example, look in this very Growing Under Lights forum for posts by user naoki. You can find them with the maroon Search button in the top menu. Select Advanced.

[dshallpost]

What about the Sunblaster LED light strips? Has anyone used these?

[Dollythehun]

I use them. I absolutely love them!

[dshallpost]

Hi Dolly, thanks for your post. Can you tell me more? How many, how close to the plants, do they heat up at all-- do you use fans to cool?

[Dollythehun]

I am not an expert at this. They give off virtually no heat, they are easy to install and come with all the hardware. My shelves are fixed so, I raise and lower the plants, not the lights. If you look at my previous posts you'll see a variety of plants. They all bloom regularly with good root growth, and the light seems quite natural. I don't know what else to tell you. I originally ordered mine from Harris Seeds.

I do have a ceiling fan in that room. But the heat generated is from my t5s which are quite warm!

[Ray]

First a correction to ES' color temperature comments:

The color temperature, in degrees Kelvin, does indeed matter to plants, as it is a way to specify the spectrum of the light. 6500°K is the spectrum of sunlight through a clear, open sky at noon on a summer day, with blue back-scatter from the sky.

However, that color temperature is only applicable to black-body radiators like the sun, as well as incandescent-, sodium vapor-, and metal halide bulbs.

In fluorescents and LEDs, the the °K is a "corrected" or "correlated" color temperature, and is, as he stated, correlated to what it look like to the human eye, not a representation of the true spectrum.

However, when you're talking about fluorescent or LED plant lights, the manufacturers make sure the spectrum is adequate for the plants, and the temp is often specified just so you know what to expect.

Both the Hydrofarm and Sunblaster fixtures are quite good. Good luck finding a Hydrofarm unit - all of their warehouses are out-of-stock. Also keep in mind that LED flood lights (I used 19W [actual] flood lamps from Cree, purchased at Home Depot) can be quite acceptable, and offer you a great deal of flexibility. Three of them will offer the same light output as a single Sunblaster strip.

[naoki]

If you know how to splice wires, Bridgelux EB series Gen 2 is a great deal. You don't need a heatsink for this one, so you don't need much assembly; you just have to connect an AC connector to the driver, and hang it up (or tape it to a surface).

For a 4' strip, you get 4920lm from 27.3W (180lm/W) for about $35.
Sunblaster 4' is 5150lm from 48W (107lm/W) for $75.

107lm/W is a very low efficiency from the current LED standard.

Each strip will cover about 1.5-2' x 4' area.

Here are the links.
4' EB strip 4000K:
BXEB-L1120Z-40E4000-C-B3 — Octopart

Driver (Meanwell APC35-700):
APC35-700 — Octopart