T-5 Bulbs

[kzickovich]

I have a current usa light fot my reef tank it has 2 150w HQI bulbs and 4 54w T-5 bulbs. It's time tp replace the bulbs and I looked at the T-5 bulbs and two are 460nm and two are 420nm my question is what does nm stand for

[scotmc]

nm is a nanometer 1 Billion of a meter

[Slice of Ocean]

What's the difference between the 420 and 460?

[kzickovich]

don't know this is the first time I'm changing my bulbs in this light I bought it new about 6 months ago I'm trying to figure out what to buy

[coraljunky]

Originally posted by Slice of Ocean
What's the difference between the 420 and 460?

420 is an 03 true actinic. 460 is more of a purple.

[Slice of Ocean]

Ohhh...Thanks!