Bulb replacement
 

Hi there,
Sorry for may be dumb question - but how often do you change bulbs? I have sunblaster T5 (fluorescent), they are working, but they are old (several years - about 5, I think). What happens if not change bulbs every 6-24 (I saw different opinions ;) ) months?
Thanks in advance!

I have fluorescent T5HO lamps (sunblaster as well as another type from Hydrofarm) that run twelve hours a day (timer). Most of my plants go outside for the summers but, since I have a dog that likes to destroy orchids, I keep those indoors. I change all the lights every two years. The bulbs usually list the hours that they should last but they do decrease in efficiency over time.

I also have older fluorescent lights. They do lose efficiency, but my lights still seem to be functioning well enough for my plants to grow, good enough for my needs. I only have plants indoors for a few months, though. Not year round.

If it were me, I would replace when I felt the plants were not getting what they needed.

Want to see something very interesting? Compare a bulb which has been run a year or so with an identical new bulb.

How?

Run 2 identical bulbs in a fixture. After a year replace 1. Compare the new to the old. Then decide on your replacement interval.

sorry, still did not get it - what should I compare? I have old ones, tomorrow (I hope ;)) will have new ones... I have light meter...

Believe me, once you observe the two side-by-side, you'll know. The intensity alone will tip you off.

Most people recommend changing the bulbs every 9-12 months, no longer. Your eye cannot see the difference when they have dimmed so much the plants begin to struggle.

Ok ;) I'm off to buy new bulbs. Thanks to all!