Leggy Seedlings related to Aging Light Bulbs ?

[St. Phatty]

I have some seedlings that are "Leggy" ... Too tall for their number of leaves.

They're under an old 250 watt metal halide. The bulb is about 5 years old.

It's an area of about 5 square feet.

Temperature wise, the lights are off in the afternoon and evening -
no major heat to contend with. The cycle is about 18/6.

I knew seedlings did this, when they are "looking for light".
Since they have plenty of light, I'm wondering - is it somehow the wrong frequency ?

I'm wondering if the age of the bulb, somehow relates to less PAR (Photosynth. Active Radiation)for the plants.

The pots are 1 gallon. Dirt is Miracle Grow Garden Soil.

 

[Therealzemi]

And how much have you used it over those 5 years? Personaly i change bulp every second grow (600 watt).

 

[Capt.Ahab]

It depends not on how old the bulb is but on how much you have used it.
I change every second-third grow.
If you have used it for five years try a new bulb. You will be surprised on how much more noticeably bright the new one will be.

 

[amanda88]

Wrong light color ...grow with an even balance of kelvin rather than the warm red/hps 2700k average,mix in an equal amount of 6500k, leaf the hps for later

 

[St. Phatty]

Sounds like it's hours of bulb "on-time" that counts.

I would say I use it about 1/3 of the time. 18/6.

And that the bulb is at least 5 years old.

365 x 5 + 1 (we had a leap year ... also it "helps the math")
+ 1 (arithmetic needs more help)

= 1827 days.


Divided by 3 = 609 days total use (over a 5+ year period) at the 18/6 cycle = 10962 hours on the bulb.


OK, so yes, point taken, a person could buy a new bulb in this situation

I'm eating Denali Extreme Maximum Fudge Moose Tracks chocolate ice cream, so it's not so painful.


If I buy a new bulb and the seedlings stretch less, that would be very interesting.

I can't be the first bulb-slacker though. This has to have happened before - people wearing out their bulbs, and leggy seedlings. I'm just wondering if there's a connection.

The seedlings are getting a healthy amount of light, but something tells me they are not crazy about the light they are getting.

That makes me think the bulbs change frequencies as they age.

I just can't let it go.

 

[Therealzemi]

Some bulps loose as much as 20% PAR over just 1 full grow. After that the degrading slows down quite a bit. In your case, i would for sure go get a new bulp. After 11000 hours of use, the plants are not getting what they need. Hence the more stretch you see.
Remember to always have 1 used bulp in backup... Just in case your main bulp blows on a saturday evening
Good luck

 

[Therealzemi]

Theres lots of info about it if you google. Too stoned to go find it for you right now.... Smoking some Critical atm

 

[St. Phatty]

Some bulps loose as much as 20% PAR over just 1 full grow. After that the degrading slows down quite a bit. In your case, i would for sure go get a new bulp. After 11000 hours of use, the plants are not getting what they need. Hence the more stretch you see.
Remember to always have 1 used bulp in backup... Just in case your main bulp blows on a saturday evening
Good luck

Yes, that's good advice. Obviously I don't have to know all the technical details to get to the bottom line - a new bulb, or a new light.

I thought bulbs just diminished in intensity, so that a light that once vegged a square yard could be used to veg a smaller area.

Cost me all of $8.50 + shipping to fix this disturbance in the Force.

https://www.1000bulbs.com/category/250w-metal-halide-horizontal-burn/

If I did want to check out the difference analytically, I'm thinking I would need to meet up with someone with access to optical analytical equipment. An HP Applications Engineer, for example.

If they had a public Electromagnetics clinic, with access to tools that measure light intensity at different frequencies, a spectrum analyzer it's called at lower frequencies ... basically I would need access to a spectrum analyzer that works in visible spectrum. And calibrated sensors.


If the plants "like" the new 250 watt bulb, I will be real curious what is the difference between the 2.

Is there a Smithsonian for Indoor Grow technology where they study things like this ?


The one that's being replaced is a "Ventura". I would be comparing an old Ventura to a new whatever. Not very scientific.

Looking at Plusrite 4000K Color Temp. vs. Plusrite 4200K Color Temp -
https://www.1000bulbs.com/category/250w-metal-halide-horizontal-burn/

Which color temp would be preferred, for Veg'ing, Clones, and Seedlings ?

 

[aridbud]

Sounds like it's hours of bulb "on-time" that counts.

I would say I use it about 1/3 of the time. 18/6.

And that the bulb is at least 5 years old.

Yes, time to swap out. Do you have a light set up with light canopy....so horizo0ntal light?

What is the manufacturer of the light system (ballast) you have now? I'd go on their recommendation for replacement bulbs.

Generally MH for veg, HPS for flower. Or when we used HID lights we had one of each side by side-HPS/MH) in 250 w light each....Diamond brand ballast.

http://www.a1b2c3.com/Marijuana-Grow-Lights-001.html