Quote Originally Posted by RackitMan
I understand that this better coincides with the accepted chlorophyll B absorption peak.
That's incorrect. 660nm is closer to Chlorophyll A's red absorption peak.

LEDs do not compare (generally) to HPS flowering as far as yield. (Please - let's not go off in that direction here. Thank you!)
That's also incorrect. Check the European cannabis boards, especially the Dutch and Spanish boards. There are numerous documented side-by-sides where 1K watts of LED easily surpasses 1K watts of HID. Their only bitch is how expensive quality emitters are. Is uw Nederlandse taal goed?

Rackitman, if you don't want to hear from people who've successfully flowered cannabis under leds, who do think is going to give you any insight about 660nm? Some dork with a 14 watt China panel?

HPS has virtual no Deep Red or Far Red and do very well - yet this is somehow necessary for a good flowering LED light. Even 'inferior' 630nm red is relatively low in HPS.
Also incorrect. The radiation emitted by HPS even includes a generous amount of non-visible IR, AKA "heat."

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