T5s and how close for seedlings...

[Kingrow1]

I dont know what others think but for me the proper amount of lumens for a seedling is around 1500lm. Ive seen threads recomend much higher but in practice i believe im close if not spot on.

T5s are rated around the 1800lm mark at a distance of one foot away/30cm if you own the 24watt version tubes. This would mean that one t5 at 30cm distance above the top of the plant will provide more than enough light for the first week or so.

I have a t5 four tube 96watt unit which is rated at 6600lm at a distance of 30cm. So for seedlings i would put this unit just over 60cm to bring the lumen level down to what a seedling wants.

This has all been working just fine and still i am getting no stretch whatsoever. At 30cm away the seedlings are so short and compact you can tell the t5s are forcing the plant back.

There is a lot of obvious damage that providing too much light can cause seedlings and small plants that instantly dissapears once the right lumen level is reached and seems apparent on seedlings kept to close to t5s.

Personally i wish i could sprout seeds at 12" away from a 96w lightwave t5 unit but at almost 7000lm per square foot they are soon suffering.

Distance to any light source per plant age and cycle is all about lumens.

 

[Connoisseurus Rex]

Right on top of them. 1"-2" away is perfect as long as there is circulation around them.

 

[Kingrow1]

Right on top of them. 1"-2" away is perfect as long as there is circulation around them.

Hey you dont need to try and cite that here as god only knows how many threads give that 1-2" from a t5 advice but have you ever taken the time to put a lux meter 1-2" under a t5 because you will be shocked and exceeding what most young plants can handle before being photoinhibited.

My t5s kick out 6600 lumens at 12" and seedlings need less than this.

All ive written is from experience, hell youll get great seedlings at 12" from a single t5 fact.

 

[Connoisseurus Rex]

Maybe you're running different bulbs or something. I run a 2ft 8 bulb (23W per bulb) at 16k lumens (allegedly) 1"-2" from my seedlings. They grow fast as hell and are super healthy.

I know that if I back it off to 5"-6", they stretch. Same growth rate more or less, just stretch. I've never used a meter though so it's not exactly scientific. Just an observation.

 

[Kingrow1]

I only know the maths for my 4x24watt t5 light wave unit which gives 6600lumens at one foot or 12" away. The industry standard for all lumen measurements is at 1foot for flourescents and 1m for hps and why hps manufacturers give a reading of lumens per meter squared and t5 manufacturers give it in feet squared.

Anyway mine gives any plant put underneath it at 12 inches 6600 lumens so id be foolish to try and get any small plants closer.

Your 23watt bulbs sound strange for T5s and would have thought they would be the normal 24watt although there are some slightly different formats i so rarely see them, possibly it is 23watts??

At 12" or 30cm from my bulb my plants are really compact and abnormally short and i have no stretch whatso ever, infact looking back i cant think of a time ive had anything stretch under t5s and people flower bigger plants at futher than 1-2" away from the bulbs.

 

[Connoisseurus Rex]

I'll go check the wattage. I may be wrong.

The are indeed 24W by Lightwise.

 

[Connoisseurus Rex]

That's just my experience. Maybe these are just shitty bulbs. They seem to grow just fine though.

 

[Kingrow1]

Even the cheap t5's ive had did just fine for growing weed and wouldnt worry or change anything, 24watt is pretty much standard for that size.

 

[Connoisseurus Rex]

All I know is that I love them to the third node and then they're for supplemental use or for clones in my tent. I've seen some pretty wicked T5 grows, so I'm not dissing them in any way. I've just noticed best growth at a much closer proximity.

 

[Kingrow1]

All I know is that I love them to the third node and then they're for supplemental use or for clones in my tent. I've seen some pretty wicked T5 grows, so I'm not dissing them in any way. I've just noticed best growth at a much closer proximity.

I didnt expect any to believe me but by three nodes im 15 to 20cm tall with big fat leaves nicely extended ftom the stem almost the size of my hands, like an inch or so between internodes and growing upwards at a very fast rate, by now were almost 12" from the bulb with its first repot.

At 1-2" from the bulb my plant has small leaves, compact growth with leaves near the stem and internode space is 1cm or less and probably a third to quater of the size of the one grown futher away. At repot i notice the plant is quite small but has a really large exstensive root system.

For me the choice is easy.

 

[Connoisseurus Rex]

I didnt expect any to believe me but by three nodes im 15 to 20cm tall with big fat leaves nicely extended ftom the stem almost the size of my hands, like an inch or so between internodes and growing upwards at a very fast rate, by now were almost 12" from the bulb with its first repot.

At 1-2" from the bulb my plant has small leaves, compact growth with leaves near the stem and internode space is 1cm or less and probably a third to quater of the size of the one grown futher away. At repot i notice the plant is quite small but has a really large exstensive root system.

For me the choice is easy.

A lot of that is going to depend on strain, time in veg, light cycle, and other variables.

From what you're saying, mine are exactly as you stated under those conditions. Maybe you're on to something. I'm popping a few beans for an upcoming hydro excitement so maybe I'll back the lights off to 12".

If I start seeing a good stretch though... They're coming back down.

How long does it take you to reach the third node under 12" on average?

 

[2ANONYMOUS]

No need to put them right on top that is looking for trouble i would suggest 3 - 6" away and observe you got to realize some T5's new are actually pretty power full so its finding the right height where as plants do not stretch to bad or do not get to hot
T5 do put out heat enough heat that in 12 hrs you small medium could be dried right out or plants fried treat them like a baby and slowly lower them as they get used to it just like mother natures way its slow n easy

 

[KryptoBud]

I didnt expect any to believe me but by three nodes im 15 to 20cm tall with big fat leaves nicely extended ftom the stem almost the size of my hands, like an inch or so between internodes and growing upwards at a very fast rate, by now were almost 12" from the bulb with its first repot.

At 1-2" from the bulb my plant has small leaves, compact growth with leaves near the stem and internode space is 1cm or less and probably a third to quater of the size of the one grown futher away. At repot i notice the plant is quite small but has a really large exstensive root system.

For me the choice is easy.

Do t5 floros lose intensity with time and age?

 

[Kingrow1]

Do t5 floros lose intensity with time and age?

Yes t5s loose intensity with time and age but the lose is small and i cant remember the exact lumens lost over 6 -12 months but even old flouros should be usable.

I wouldnt assume it would drop to anywhere near 50% even after a few years with t5s but again id have to check to be 100% sure.

Did i see somewhere that a thicker phosphorous coating last longer but a thinner coat emits more light so a fine balance of the two makes a good bulb.

Anyway ive run some tubes for years and found i have to move plants slightly closer but not much. The best info and tests on flourescents ive ever found come from fish and coral keepers plus those over at planted tank, they go more indepth than weed growers even testing spectrums and lumen loss over time.

I can get 2 new blue 24watt t5s from my local hydro shop for under £10 about $12.50 so its really not hard to replace a couple every few months and keep things running sweet.

 

[KryptoBud]

I was just curious to know if the drop in performance was significant if at all over say 6 months.

 

[Joe Blows Trees]

So after reading this thread, I'm seriously considering getting two 4 foot, 4 light t5s instead of a 600watt MH for the veg room. I'm thinking heat wise, the two t5s will be the same or less than the 600watt MH and I can easily get replacement bulbs for the t5s vs the MH.

 

[KryptoBud]

They have 4ft 8 bulb lamps would be cheaper

 

[churchhaze]

https://www.rollitup.org/t/smashing-fluorescent-lamps.864130/

 

[Kingrow1]

I was just curious to know if the drop in performance was significant if at all over say 6 months.

There should be little to no drop in lumens after 6 months with flourescents, nothing that plants or humans would notice.

https://www.rollitup.org/t/smashing-fluorescent-lamps.864130/

Ill give you that, those self ballasted CFL,s are impractically designed with the ballast on top but T5/T8/T12's absolutley rock so there is no need to smash them up whatsoever. Im not keen on CFL's and have run most types, certainly there is a vast difference between a 24watt CFL and a 24watt T5 in terms of light and quality.

So after reading this thread, I'm seriously considering getting two 4 foot, 4 light t5s instead of a 600watt MH for the veg room. I'm thinking heat wise, the two t5s will be the same or less than the 600watt MH and I can easily get replacement bulbs for the t5s vs the MH.

Dont base any purchase on my threads, i use t5 because i have a small veg area and dont veg for long so they are perfect for my situation.

 

[Kingrow1]

No need to put them right on top that is looking for trouble i would suggest 3 - 6" away and observe you got to realize some T5's new are actually pretty power full so its finding the right height where as plants do not stretch to bad or do not get to hot
T5 do put out heat enough heat that in 12 hrs you small medium could be dried right out or plants fried treat them like a baby and slowly lower them as they get used to it just like mother natures way its slow n easy

My unit is a lightwave T5 with four bulbs of 24watts so 96watts total, it pumps out 6600lumens when plants are placed 12inches away. I have never had any plant stretch and have to go a lot futher than 12inch to get leggy plants.