Re: [APD] Aquatic-Plants Digest, Vol 31, Issue 36

["Daniel Larsson" <defdac at hotmail_com>]

Jerry Baker wrote:
>I know that in terms of lumens per watt, HPS has everything else beat by 
>a pretty wide margin. HPS bulb efficiency can be up around 140 lumens 
>per watt while PC's are usually around 70 - 90 if I recall correctly.

The thing is  HPS:es usually have only a big ugly spike in the
yellow-green part of the spectrum that plants reflect or have
to use accessory pigments to use (inefficient). So lumens
per watt is only a measure of how efficient the bulb is in
making human visible light, and we are very sensitive
to yellow-green, which plants reflect.


Best regards
Daniel Larsson

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