Converting from T12 to T8 LED.

[J Tiers]

Any link to a reference? Planning to grow some venus flytraps, and like prices on white LEDs better than the "special" ones.

I'd have to dig around, we get a variety of gardening mags, and I don't recall which it was. If I can find it I will mention it, but I make no promises, as I don't really have a starting point to look for where it was.

I googled for test results for plant lighting, and got almost 100% results related to cannabis sativa. The only useful item I found was actually a Wikipedia article. The article was interesting in that it specifically mentions the need for green light up to perhaps 25%, to improve growth in many plants. That is what I recall from other reading, and the article footnotes it, so you can follow up.

https://en.wikipedia.org/wiki/Grow_light

[Mark Rand]

I have a relative in the weed business in Cali, he says the LEDs are not replacing HID among the pros.

The pros over here tend to bypass the utility's electric meter until they get caught

[TR3driver]

With the future of T12's being limited I'm thinking of converting them to T8 LED instead of replacing the T12 ballast. Or I could just toss the old T12's.
Opinions?

FWIW, I've done several that way. As noted above, they work great. Since most of the T12 ballasts were bad anyway, I just wired around all of them. I see now that the Amazon ad says they don't work with T12 ballasts, but the pair I tried seemed to work fine in the one fixture that still worked with the old T12 tubes.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[mattthemuppet]

I'd have to dig around, we get a variety of gardening mags, and I don't recall which it was. If I can find it I will mention it, but I make no promises, as I don't really have a starting point to look for where it was.

I googled for test results for plant lighting, and got almost 100% results related to cannabis sativa. The only useful item I found was actually a Wikipedia article. The article was interesting in that it specifically mentions the need for green light up to perhaps 25%, to improve growth in many plants. That is what I recall from other reading, and the article footnotes it, so you can follow up.

https://en.wikipedia.org/wiki/Grow_light

interesting. Seems that some green light is needed for reproductive vs. vegetative development and that a proportion of green light is absorbed under intense white light illumination, partly because it penetrates further into the leaf. Some interesting reads here:
http://hortsci.ashspublications.org/...17.full.pdf%7D

[lakeside53]

Prices are dropping... Yours may vary, but my Home Depot has Phillips 17W 2100 lumen tubes at $6.97 each. $5.92 if you buy 10 or more.
This particular unit uses your existing electronic ballast.

http://www.homedepot.com/p/Philips-4...6608/206278132

Damn, I still have spare T8 flouro tubes

[garyhlucas]

I did some consulting work for very secret government greenhouse project. Talk about grow lights, they had enough HID lights to produce the noon day sun in the desert, 10,000 foot candles at the floor! 4000 amp 480/3ph service. We're standing this new greenhouse and I casually say to the goverment guys "so what are you going to tell NASA? We are in the desert without street lights for five miles. Two acres lit to the noon day brightness is gonna prompt a call from the people on the ISS!" The guy kind of turned green. Two weeks later they installed 100% blackout cloth that could be open and closed over the whole place. They finished whatever they were doing about 10 years ago.

[Abner]

I did some calculations about 2 yrs ago on changing my T12 to T8. Using my electric rates, apples to apples (stated) light output to get my energy savings and came to the conclusion that unless a ballast was bad it did not pay to upgrade for my limited winter time use. The payback was too far out. Commercial guys running 40 hr weeks are a different story.

As far as true greenhouse lighting goes they are in the commercial end of things and it doesn't scale back down. 14' eve height gutter connect with HID or HPS lighting is the norm around here in nurseries that need it.

If you are intending to grow some -ahem- 'weed' there is a goal of 1 gram per watt. There is plenty of reading online.

Right now it is like the marijuana gold rush here in Oregon. The amount of production coming on line will dwarf users ability to smoke it all up - seriously. So either the price will drop, it will get smuggled out of state, or they are planning for legalization nation wide. The weed 'industry' will have a shake out separating out those with better business sense from those who can't identify aphid damage and root rot - the stories are intensely funny, aphids are like kindergarten to any grower worth a his/her salt. Heard a story yesterday about a whole outdoor field getting root rot.

[J Tiers]

My grow-light usage is limited to starting flats of plants. Veggies, flowers, foliage plants, etc.

I use a bank of 3 LOA type shop lights per shelf section, which covers 4 flats. there are many sections. The lights start out just above the flat covers, and are raised up as the seedlings grow. It is timed such that by the time the seedlings are too tall to raise the lights further, the plants can go out to the unheated greenhouse. Lights are on a variable time per day, but usually 14 to 16 hours

The traditional "grow-light" does not do nearly as well as the cool white/warm white combination, probably due to simple light intensity. I have thought of adding a 4th light to each shelf, moving the existing over to allow angling the two "edge" lights so as to fill in the "dark hole" at the sides that appears as the lights are raised, and add intensity, but have not tried that yet.

Since I do not have a "farm field" setup, HID does no good. It is "area lighting", but I have a more compact setup, which is perfectly suited to the fluorescent usage. They work well, but the LED types are quite different in light distribution, both directionally and spectrally.

[QSIMDO]

I've been putting these in both at home and at work-

https://www.earthled.com/collections...ant=2174807620

https://www.earthled.com/collections...ant=2403570948

These are ballast bypass bulbs,so the ballast goes away and the bulbs wire direct.

+1 on these LED's...simple to change and no ballasts to replace, but I'll also keep what T 5's I have right where they are.
They do give good light.

[Abner]

My grow-light usage is limited to starting flats of plants. Veggies, flowers, foliage plants, etc.

I use a bank of 3 LOA type shop lights per shelf section, which covers 4 flats. there are many sections. The lights start out just above the flat covers, and are raised up as the seedlings grow. It is timed such that by the time the seedlings are too tall to raise the lights further, the plants can go out to the unheated greenhouse. Lights are on a variable time per day, but usually 14 to 16 hours

The traditional "grow-light" does not do nearly as well as the cool white/warm white combination, probably due to simple light intensity. I have thought of adding a 4th light to each shelf, moving the existing over to allow angling the two "edge" lights so as to fill in the "dark hole" at the sides that appears as the lights are raised, and add intensity, but have not tried that yet.

Since I do not have a "farm field" setup, HID does no good. It is "area lighting", but I have a more compact setup, which is perfectly suited to the fluorescent usage. They work well, but the LED types are quite different in light distribution, both directionally and spectrally.

That is a serious affair for a homeowner! You can save quite a bit of money that way and greenhouses are just nice spaces to work inside of.

[J Tiers]

When the veggies can be planted-out they go out to the regular growing areas, and the greenhouse is not used again until maybe late in the year, for anything that is in tubs and can be moved back in to go farther toward frost..

The other plants either go to our gardens, the neighborhood gardens, or to the city wide organization that takes care of 300 gardens across the city. So we sometimes start a LOT of plants.