HID Light Longevity and Spectrum Question

tom_termine

Hi all -

I was going to post this question to the "Indoor" section of the forum, but I wasn't sure how frequently that is visited. I am not trying to rush the season (both me and my trees are enjoying the heat right now!) but I was hoping someone could help with these questions.

I have two HID grow lights hanging in a sunroom that I use when I bring in my trops, subtrops and some pachycaul succulents I grow. Ones is running a 600W Sunmaster Cool Deluxe MH Conversion Bulb, the other a 1000W BT37 Sunmaster Blue Burning Metal Halide Lamp. I ran them last fall - winter - spring for my plants for about 2500 hours overall.

When have these bulbs reached the end of their useful lifespan for these plants? I was thinking about replacement - but do I need to do that yet? If the manufacturer states that they lifespan is 10,000 hours for example, is that number applicable to how useful they will be for plant growth?

Can anyone recommend different brands of Metal Halide light bulbs with which they have had great results for ficus, braz raintree, euro olive, buttonwood, jaboticaba, natal plum, schefflera...etc?

What about the whole blue burning vs. red burning thing? These are both blue burning, as I was told that blue is best for green, compact growth. Now I am seeing some folks swear by Philips ceramic MH bulbs which burn "white"...

Any advice is appreciated.

Tom

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Tom

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dtree

Hi Tom - even at 10,000 hours those bulbs could be burning pretty bright. HID lamps will be noticeably dimmer, or they may flicker slightly when nearing the end of their lifespan. Blue bulbs and standard metal halide will give more compact growth, with the blue being slightly more compact I have found. There are new fluorescent lights (T5) on the market which have a red and blue bulb at specific frequencies for plant growth, red for flowering and blue for vegetative. They seem to produce excellent results with the added benefit of very little heat.
-dtree

TreeBay

HIDs are efficient, but they have a strong Lamp Lumen Depreciation (LLD =the % output of the lamp relative to initial output after 40% of rated life.)

HIDs might decline to 65% of their original output after 40% rated hours. You'd need to compensate for this accordingly. (rated life might be something like 10,000 to 20,000 hours)

Flourescent lamps have a less pronounced curve, with an LLD of 80-90%, so typically see more constant light output there during their useful life.

There are other factors that will reduce output, including the reflector or element getting dirty over time.

Some references:

http://72.14.203.104/search?q=cache...s&ct=clnk&cd=20

http://www.energy.gov.on.ca/english...ghtingGuide.pdf
A big lighting guide PDF - search on LLD

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dtree

I have found through experience that the high quality professional type systems with new technology ballasts and bulbs do not wear out that fast. That type of wear is more typical of cheaper, older style bulbs and ballasts. I guess it is true that you get what you pay for.

tom_termine

Thanks for the replies. So, it doesn't sound like I should be in a hurry to replace these bulbs after 2500 hours (they were rated at 9,000 and 10,000 hours, respectively).

That said, I am always interested in a "better" bulb. Can either of you recommend a different brand that you find superior? Any experience with the MasterColor Ceramic Metal Halide HPS-Retro White™? Not sure if they make it in 1000 and 600 watt (I would need a conversion buld for the 600W fixture).

One other question about duration - do you tend to start at 14 hours or so and then reduce it a bit as the winter season approaches to allow a bit of a "rest" period for tropical and subtropical bonsai, or do you keep it pretty steady? Typically, I keep it pretty steady and I am wondering if I am stressing my trees by doing so (at least the subtrops like olive and bougs for instance).

thanks again.

Tom

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Tom

TreeBay

Hi Tom

Jerry Meislik has some nice articles: http://www.bonsaihunk.us/cultural.html

Photoperiod can influence flowering and dormancy. When I used lights outdoors it was not really for growing purposes (so I don't have much experience with that subject) but rather just as heat sources (incandescent lights are pretty inefficient and make nice heaters). So I was actually running them in the very early morning when it was coldest.

Regards,

Matt

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dtree

Hi Tom - from my experience, spend a few extra bucks and get the most expensive bulb. Phillips is just one of a few high-end manufacturers. HPS lights are not as desirable as Metal Halide, as even the white or blue HPS is still more of a "flowering" bulb.

tom_termine

Thanks for the link, Matt. I have read Jerry's materials before - but he doesn't spend much time on the useful lifespan of MH bulbs for trop and subtrop bonsai applications, or on the variations I now find in different brands of MH bulbs and color spectrums (i.e., the blue vs. red vs. white thing...).

dtree - any opinion on the two bulbs I am currently using vs. the Philips ceramic White bulb? I have a 600W Sunmaster Cool Deluxe MH Conversion Bulb, and a 1000W BT37 Sunmaster Blue Burning Metal Halide Lamp with about 2500 hours used up on each.

Thanks!

Tom

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dtree

Hi Tom - your Sunmaster bulbs are high quality bulbs, others are Phillips and Hortilux. There is some good up to date info on lighting tecnology in Maximum Yield magazine, or at maximumyield.com , this is not a dope-grower's mag but for industry professionals.