Grow Bulb Life Expectancy

[gateway77]

Just wondering if anyone knew how long a 15watt grow screw in bulb lasts?
Can you use them until they burn out? or should you replace them after a year or so?

[emc7]

Can you use them until they burn out? or should you replace them after a year or so

For ordinary light, yes use them until they burn out. For plants, maybe, if the plants look less healthy, change the bulb. The spectrum and intensity do change over time, you can generally get a graph from the manufacturer. But unless you have corals or plants that need a lot of light, using them to failure is fine. I was hoping for more from the light website than

" * Fluorescent lamp lumens decline during life"--GE

they do give you a rated life in hours so the bulb should be decent for that long.


The phillips site has more what I had in mind. http://www.nam.lighting.philips.com/...pdf/p-5611.pdf The graph shows that this particular light loses 10% of light output in 5000hrs and 20% in 20000hrs and continues to decline. If lighting is really critical (like in a UV sterilizer) you replace the bulbs on a schedule so the output never falls too much. If its just to see your fish, who cares if it gets a little dimmer.

[jones57742]

Originally Posted by gateway77

Just wondering if anyone knew how long a 15watt grow screw in bulb lasts?
Can you use them until they burn out? or should you replace them after a year or so?

Gw:

Some of the following supports Em's statements and some is in addition to Em's statements.

A portion of the following is based on the literature but most is based on experience.

You did not indicate if the "screw in" bulbs were fluorescent or incandescent.

Typically the spectrum of fluorescent bulbs will begin degrading in nine months and will have degraded significantly in 12 months although the bulb may last much longer.

I do not know how long incandescent bulbs will last but little degradation of the spectrum of the bulb will occur until the failure of the filament.

TR