Anyone do testing of their T-5 bulbs with meters? I am curious to know how long after being used will the bulbs lose their PAR(intensity) or start to shift spectrum??? 1year? 2?

IME it depends on what bulb you are using. UVI bulbs generaly last 9 months to a year. But it also depends on alot of factors like how long is your light cycle do you have fans blowing on them to keep them cool. There is alot of factors than contribute to bulb life.

I haven't seen any data on this yet. I wish I had a Par Meter but I don't. Most places that I've read indicate that they have a life expectancy of between 16 and 24 months. I think that we will definitely hear more of this in the future. Life expectancy does go down of course if you're overdriving them. If I come up with any hard data I'll post it. If anyone else has any research data I'm sure that there are a lot of us who would like to know.

Thanks for a great question.

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Doc

Dr Hank's 200 gallon Reef Tank
http://www.aquariumforum.com/f46/drhanks-tank-3440.html

Eh. I am dying to find a reason to switch my bulbs for an upgrade but can't justify it unless I know my bulbs are bad.. Hmm maybe I will look into a PAR meter.

You can give them the old hammer test. Hit each bulb 1 at a time with a hammer. If it breaks you know the bulb is bad. If it does not break repeat process.

I hear you. I've got the ballasts, the reflectors and a couple pair of end caps and stand offs. I'm accumulating what I need gradually and hope to move to T5s early next year. I'll give up my shimmer for a cooler running set up with less current draw. The only other way is to go with a smaller tank and I don't want to do that.

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Doc

Dr Hank's 200 gallon Reef Tank
http://www.aquariumforum.com/f46/drhanks-tank-3440.html

Ha! The hammer test. That is funny. Nice one!

thought you might like that idea