420 Magazine Background

Do 1000w bulbs lose lumens as they age?


New Member
Clerk at a local shop told they do.. I had never heard that before.. or was she simply trying to get me to buy new bulbs?

Have had the same bulbs(Ultra sun 1000w HPS) in for over 5 grows.. almost 2 years... I keep thinking they will blow out soon.. but nope, they seem as strong as ever.

Should I pick up a light meter?

Bought new replacement blubs when I bought these.. so can change out at any time.

Anyone have the answer?


New Member
Yes they do lose lumes over time, that why each bulb is rated for a certain amount of hours. I have a hydrofarm digital light meter and it works great. Sweet to know what parts of your garden is getting weak light. Lets say for flowering most growers use there bulbs for 2-3 grows and then replace.


New Member
Hey, thanks for the swift replies Dog and Hog..

What sort of loss are you talking about?

Im in bloom right now(4thweek) and my girls sure look normal.. with apparently very old bulbs?

Perhaps they would be doing even better with new blubs.. ?

Really, what amount of drop do you see from an older(still blasting with light) bulb?

Not doubting, jes wondering?

Also thanks for the hydrofarm light meter info.. found it on line for 40 bucks.. very good price.. have looked before and only found meters in the 200$ range

Just ordered one..


Plant of the Month: June 2010 - Nug of the Month: July 2010
I've done great things with old bulbs. In an effort to maximize my consistency, I've tried to eliminate variables as much as possible...one of the variables is lumen degradation.


New Member
Yea you can not go wrong having a light meter around. When lumes deapreciate over time is all has to do with the brand of bulb. Each company has a graph chart that shows the lumes drop over the life span of the bulb. I bought a cheap bulb forget the brand but by 25% of the rated hours used it lost over 40% of lumes and with horitlux it is 25%used only drops 10%. i forget the exact measurements but it is a huge swing with cheap and quality bulbs. So you are way better off to get quality bulbs than to get by on cheap ones.


New Member
The graph below (courtesy of GE) shows the degradation of various types of bulbs over time. One of the worst culprits in the MH.

Note that this graph is in thousands of hours. The mean life of the bulbs lands at 8 (8000 hours) around 333 days or 1 year.

Last edited by a moderator:


New Member
A very hearty THANK YOU to all .. I knew I would get the best answer to this question from here....

Hopefully others will see it also..

Just switched out all my blubs..

Thinkin I should look into lighting company stock?



New Member
I bought a 200k lumen meter a couple years ago just to check on my 1000w hps bulbs. Have yet to see any degradation in lumens of my 2 year old bulbs. I suppose they do degrade with time, everything does. But I've yet to see any on mine yet.
Top Bottom