Old ass light!


Active Member
So the last time i had an indoor grow was 2013. Mostly been an outdoor guy for the last 25 years or so. But with the last grow in 2013 i used a 400 watt HPS eye hortilux single ended bulb for one grow. Packed up the bulb after that one grow and the thing has sat since then. So heres my question, does the age of bulb matter if the hours on the bulb are low?


Active Member
I would venture to say that some new bulbs stay on the shelf for 7 years. I would expect no degradation of the bulb when not used.
Not a perishable item. Now- I could be wrong as it happens often ;-)

Speaking of the life of HPS's For 10 years plus I had a Phillips 150w CMH in a small cab. I recently whiched to a LED light- in researching I learned about the PPFD- LUX- PAR ect. I also found the use of a cell phone LUX meter handy to compare the two lights. (I know they are not too accurate)
Anyway- I ended up measuring the LUX of a new Phillips CMH and then again 55 days after being used at 12/12. I found a remarkable amount of
LUX loss is just 55 days - Like 15-20% I was very disappointed.


Well-Known Member
Did the bulb degrade from sitting? Probably not. Did that first run knock off say 5 - 10%? Probably.

So, my question to you is, if you lost 10% of your yield due to a bulb being diminished, would that 10% of the yield be worth more to you than the price of a new bulb? (For me it would be wise to put in a new bulb)

I would get a new bulb and keep the old one as a spare for emergency.


Active Member
Renfro- THX for chiming in. We have known that HID bulbs will loose some of their juice over time. The specs on this bulb say it has a average life of 20K hours with Lumen maintenance of 89% after 2k hours and 79% at 5K hours. I was surprised to see such a drop in just 1000 hr. The test was not run long enough to know if the drop continues at the same rate over time- I am guessing not. I follow your train of thought on replacing the bulb but unless this bulb was an anomaly I'm not terribly impressed with it's service life. I have a couple new bulbs in house so I may run this test again in the future. At this time I am trying to commit to my new HLG 288v2 respec board but am having the LED beginners blues. I will be posting a thread in a few minutes titled "Opinions please" I hope you find the time to take a peak at it.

Best Regards