4100K bulbs
 

Are 4100K bulbs any good for growing macro algae in my refugium?

umm, yes?





:mrgreen: do I win?

You wanted a serious answer? Sorry - OK, likely you can grow some macroalgae with this spectrum, but not really well from what I remember. Daylight/6500K (and enough of it) will do a better job.

And a 400W 13000K MH bulb should have as much punch as a used 175W (I would hope for more), in answer to another post of yours... is the 175 a 10K?

yah my 175 are 10K ushios. The 400w is 13K really nice colour, but was suprised that it wasn't overwhelmingly bright