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Re: What is more important: lumens or CRI?

"Sietske Tol" <wj.spoel at hccnet_nl> wrote:

> Please, share your insights with me.
> Where I live I can choose between two kinds of Philips 58 Watts tubes.
> The 900 line with a CRI of 98 (ninety eight) and a lumens of 3700 for
> instance with a K of 4000, 5000 of 6500
> The 800 line with a CRI of 85 (eighty five) and a lumens of 5200 with the
> same possibilities for K.
> I can have 4 tubes of 58 Watt in my heavily planted tank.
> Any ideas of the best combination of tubes? I do not use CO2 injection.
> Sietske Tol at wj.spoel at hccnet_nl

900 phospors are somewhat less efficient to transform Watts into photons.
But the difference is not that large, about 10-15%. So most of the difference
you see between the lumen ratings of these two bulb types, about 40%, is due 
to the fact that the 800 phosphors are better matched to the human eye 
photopic curve. For plants, the difference is not that large. So it all
boils down to what *you* want to see: brighter lit tank (go with the 800s)
or better rendered colors (go with the 900s). I personally would mix both
types. In my aquarium I have two 55 Watt PCs, one is a 800 6500 K and the 
other a 900 5300 K. Looks pleasant to me.

- Ivo Busko
  Baltimore, MD