LIGHTS - how close is too close - Page 2

Worth1 · March 29, 2018

Too many dials knobs calculations and adjustments for something that should be simple.
All in the name of robbing folks of their money.
I dont mean to sound rude but I have seen it time and time again.
Worth

SQWIBB · March 29, 2018

Quote:

Originally Posted by Worth1

Too many dials knobs calculations and adjustments for something that should be simple.
All in the name of robbing folks of their money.
I dont mean to sound rude but I have seen it time and time again.
Worth

Bloom time, veg time.... tells me the light is geared towards "Marry Juh Wannah" growers, but for simple seed starting I agree, its just too much unneeded information when all you need is a Kelvin rating, to me that's what I look for in providing lights to my plants, the closer I get to 6000k the better.

Never had a problem.

Harry Cabluck · March 29, 2018

MD, sent you a PM regarding LED's. Have used them here with greater success than fluorescent tubes. Made by Austin company. They were kind enough to bring umol meter and adjust to optimum/proper light intensity. Started seeds Jan. 1. Plants now in raised beds with blossoms and tiny tomatoes.

TexasTomat0 · March 29, 2018

Harry - can you send me the company info? I'm curious to take a look. I built my own LED's so I'm curious to see how they compare.

Harry Cabluck · March 29, 2018

TexTom0, Here is one of their pages: https://fluence.science/technology/ray/. They really know their stuff. The units are just fantastic, once properly adjusted...expensive, but outlast fluorescent fixtures and tubes. Nope, not an employee, just a happy customer.

TexasTomat0 · March 29, 2018

Those are nice but expensive. You can buy kits much cheaper online if you're somewhat handy. I built my own COB LEDs, and have some of the Quantum Boards on order now because I like their low profile. They're about $2/watt and are just a board that you hook to a driver.

It is nice how they come help you set up and test the lights. Seems like they're getting ahead of the curve for a new type of home growing indoors.

nbardo · April 2, 2018

Regarding getting nauseous from LEDs, it could be from nearly imperceptible flickering. If the power supply doesn’t have properly sized filter capacitors or they used bad electrolytic capacitors that have gone bad, it will cause them to flicker at 120hz (or 100hz if you are in europe). Especially with higher power consumption this might happen. Not to get too far into the details but LEDs take DC power, and your outlets supply AC. The power supply rectifies the AC power into DC and the filter capacitor smooths out the peaks and troughs from the AC voltage into a flat constant DC voltage. If the cap isnt big enough the LEDs will use up the power stored in the cap and begin to dim as the voltage drops. As soon as the next peak in voltage happens, it will charge up the cap and go to full brightness before beginning to dim again. This happens 120 times per second for a full wave rectified DC power supply in north america. Too fast to perceive, but slow enough that it can cause nausea/motion sickness.

You can see it more easily with cheap LED christmas lights which dont usually have a filter capacitor at all and are often only half wave rectified so it happens at 60hz which most people can see.

Sent from my iPhone using Tapatalk

mobiledynamics · April 2, 2018

NB. No flicker. I think in the literal sense, it was brain shock - and the brain/sensory senses. For the 1st 10 days, I literally turned off the lights before I entered the room as I would get dizzy if not semi-nauseous.

It's now at lease more comfortable - meaning, I can walk in, and head straight to the dimmers, turn off the veg setting (more brightness and red), and the color output is a mix of primarily blue/white with minute red, but because the intensity is less and my *brain* had adjusted, I don't set such sensory reactions.

Very weird non the least....but definitely something new for me as far as running LEDS and the reaction of

loulac · April 3, 2018

I think "weird" is the right word. You could make a test with a common LED lamp in one room of your home (don't buy it, borrow it from a neignbor / friend. just in case) to see if you react in the same way. It's well-known some people can't bear waves coming from phone relays but your case is really exceptional.

All the best

saucy boy · April 3, 2018

Hi, folks. I'm not sure if this my first post on this forum, but if not it's been a while. 😉Thought I'd chime in on a few things here and there.

I grow my tomato starts in 72 cell plug trays. I use two 8-bulb 6300K T5HO fixtures to cover 9 trays. They give off a lot of heat, so much that don't need germination mats to get the soil up to 85°. I can even put 4 trays on top of each fixture and get the soil up to around 80°, which allows me to use my mats for other starts.

I used a photographic light meter to see how much light falloff I get as the fixtures are raised. In theory, the light intensity should get four times as bright for every halving of the distance, but in the real world the light intensity stops increasing at distances any closer than about 6".

At 6" distance these fixtures give off the same amount of light as we get here (Upstate NY) in our nursery at midday on an overcast day. In full sun the light intensity is over 2 "stops" brighter, which is more than 4 times as much light energy.

Under my lights the air temps can get over 100°F if they are too close. The lights won't "burn" the leaves, but the air temp is way too high for best growth, and the trays dry out and need constant watering through the day. So I aim for about 8" minimum distance once the seedlings emerge, as it is enough light for adequate growth, but not so close as to cause heat buildup problems.

Sorry if my first post seems a bit wordy, just trying to share what I've discovered.

saucy boy · April 3, 2018

Quote:

Originally Posted by mobiledynamics

NB. No flicker. I think in the literal sense, it was brain shock - and the brain/sensory senses. For the 1st 10 days, I literally turned off the lights before I entered the room as I would get dizzy if not semi-nauseous.

It's now at lease more comfortable - meaning, I can walk in, and head straight to the dimmers, turn off the veg setting (more brightness and red), and the color output is a mix of primarily blue/white with minute red, but because the intensity is less and my *brain* had adjusted, I don't set such sensory reactions.

Very weird non the least....but definitely something new for me as far as running LEDS and the reaction of

I know what you mean. Yesterday I went to the local hydro store to get some fertilizer. They are mostly cannabis oriented, but they have an expensive LED setup with peppers (legal to grow here in NY) growing hydroponically under the light. These things got huge since the last time I was there, but they look so weird under that light that it's a bit disconcerting. I didn't get ill looking at them, but it was not exactly pleasant. Wish I had one, though, they work great.

mobiledynamics · April 3, 2018

Hi Lou -

Don't have common led strips vis-a-vis for growing, be we do have LED bulbs in the garage and kitchen (PAR style) which is fine. Way OT, but call me old skool. For lights in the house, I still prefer old school halogens/incandescent. Yes, LED bulbs come in High CRI and similar color ranges of 3K-2700K, but there is definitely a pop or 2 missing from even the most highest end CRI led bulbs versus old school halogens IMO -- I did the conversion in the kitchen due to heat output from the halogens, and that has been a tremendous difference .

mekrebs · April 3, 2018

It depends on the light technology. Too much incandescent or HPS can cook your plants. Fluorescent can be as close as possible short of touching. LED's are presumed safe but I don't have personal experience using them as I am genetically too much of a cheapskate.

Basically, plants need light like they need water. Either too much or too little will harm or kill them. The term DLI (daily light integral) is the best method of calculating optimum amounts of light for plants.

Attached is a Word doc, spreadsheet and PowerPoint that explains as much of this as you can bear

bower · April 3, 2018

Just want to say how much I appreciate everybody's discussion about lights this spring. I think I was lucky I didn't have the moolah to make a major LED purchase this winter, and couldn't find suitable LED bulbs either for my T8 fixtures, so had to stick with some fluorescents and the couple new LED's.

For all that's been touted I'm not convinced that LED is a really mature technology and not so easy to just swap out your shoplights for the new thing. So I will tread carefully in planning for the future and hold off for awhile on more LED lights, until I'm sure I'm not still in the dark.

mobiledynamics · April 3, 2018

I interpreted from you post you were running LEDS. All in all - i find it's interesting to observe. With the former lights , at this stage of growth, I would say the stem might be 3+ inches higher than where my current ones are right now The leaves just keep on getting bigger and bushier with not much elongation

April 3, 2018	#27
mobiledynamics Tomatovillian™ Join Date: Jun 2016 Location: 7B Posts: 281	Hi Lou - Don't have common led strips vis-a-vis for growing, be we do have LED bulbs in the garage and kitchen (PAR style) which is fine. Way OT, but call me old skool. For lights in the house, I still prefer old school halogens/incandescent. Yes, LED bulbs come in High CRI and similar color ranges of 3K-2700K, but there is definitely a pop or 2 missing from even the most highest end CRI led bulbs versus old school halogens IMO -- I did the conversion in the kitchen due to heat output from the halogens, and that has been a tremendous difference . Last edited by mobiledynamics; April 3, 2018 at 10:38 AM.

March 29, 2018	#16
Worth1 Tomatovillian™ Join Date: Feb 2006 Location: Den of Drunken Fools Posts: 38,539	Too many dials knobs calculations and adjustments for something that should be simple. All in the name of robbing folks of their money. I dont mean to sound rude but I have seen it time and time again. Worth

March 29, 2018	#18
Harry Cabluck Tomatovillian™ Join Date: Jan 2018 Location: Austin, Texas Posts: 217	MD, sent you a PM regarding LED's. Have used them here with greater success than fluorescent tubes. Made by Austin company. They were kind enough to bring umol meter and adjust to optimum/proper light intensity. Started seeds Jan. 1. Plants now in raised beds with blossoms and tiny tomatoes.

March 29, 2018	#19
TexasTomat0 Tomatovillian™ Join Date: Mar 2017 Location: Central Texas - Zone 8A Posts: 196	Harry - can you send me the company info? I'm curious to take a look. I built my own LED's so I'm curious to see how they compare.

April 2, 2018	#22
nbardo Tomatovillian™ Join Date: Jan 2018 Location: St. Louis, Missouri Posts: 78	Regarding getting nauseous from LEDs, it could be from nearly imperceptible flickering. If the power supply doesn’t have properly sized filter capacitors or they used bad electrolytic capacitors that have gone bad, it will cause them to flicker at 120hz (or 100hz if you are in europe). Especially with higher power consumption this might happen. Not to get too far into the details but LEDs take DC power, and your outlets supply AC. The power supply rectifies the AC power into DC and the filter capacitor smooths out the peaks and troughs from the AC voltage into a flat constant DC voltage. If the cap isnt big enough the LEDs will use up the power stored in the cap and begin to dim as the voltage drops. As soon as the next peak in voltage happens, it will charge up the cap and go to full brightness before beginning to dim again. This happens 120 times per second for a full wave rectified DC power supply in north america. Too fast to perceive, but slow enough that it can cause nausea/motion sickness. You can see it more easily with cheap LED christmas lights which dont usually have a filter capacitor at all and are often only half wave rectified so it happens at 60hz which most people can see. Sent from my iPhone using Tapatalk

April 3, 2018	#24
loulac Tomatovillian™ Join Date: Feb 2013 Location: France Posts: 554	I think "weird" is the right word. You could make a test with a common LED lamp in one room of your home (don't buy it, borrow it from a neignbor / friend. just in case) to see if you react in the same way. It's well-known some people can't bear waves coming from phone relays but your case is really exceptional. All the best

April 3, 2018	#25
saucy boy Tomatovillian™ Join Date: Jul 2014 Location: Upstate New York Posts: 4	Hi, folks. I'm not sure if this my first post on this forum, but if not it's been a while. 😉Thought I'd chime in on a few things here and there. I grow my tomato starts in 72 cell plug trays. I use two 8-bulb 6300K T5HO fixtures to cover 9 trays. They give off a lot of heat, so much that don't need germination mats to get the soil up to 85°. I can even put 4 trays on top of each fixture and get the soil up to around 80°, which allows me to use my mats for other starts. I used a photographic light meter to see how much light falloff I get as the fixtures are raised. In theory, the light intensity should get four times as bright for every halving of the distance, but in the real world the light intensity stops increasing at distances any closer than about 6". At 6" distance these fixtures give off the same amount of light as we get here (Upstate NY) in our nursery at midday on an overcast day. In full sun the light intensity is over 2 "stops" brighter, which is more than 4 times as much light energy. Under my lights the air temps can get over 100°F if they are too close. The lights won't "burn" the leaves, but the air temp is way too high for best growth, and the trays dry out and need constant watering through the day. So I aim for about 8" minimum distance once the seedlings emerge, as it is enough light for adequate growth, but not so close as to cause heat buildup problems. Sorry if my first post seems a bit wordy, just trying to share what I've discovered.

April 3, 2018	#29
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,794	Just want to say how much I appreciate everybody's discussion about lights this spring. I think I was lucky I didn't have the moolah to make a major LED purchase this winter, and couldn't find suitable LED bulbs either for my T8 fixtures, so had to stick with some fluorescents and the couple new LED's. For all that's been touted I'm not convinced that LED is a really mature technology and not so easy to just swap out your shoplights for the new thing. So I will tread carefully in planning for the future and hold off for awhile on more LED lights, until I'm sure I'm not still in the dark.