it is weekend already, next week I may go deeper into each aspect, but just to pinpoint few things... - CRI - it is not dependant by color temperature, and is not necessary to have high amount of reds in it. Can have high CRI LEDs at 6500K and low CRI LED at 3000k. So, high CRI or low CRI doesn't change anything to PAR/PUR or whatever you consider. Speaking of blackbody temperatures, either 3000 or 10000 k pure blackbody have CRI around 98-99. CRI means having or not certain wavelengths in a source, but not the ratio between them. As a replacement of CRI, more and more companies are using Color Quality Scale (CQS) - which is the possible CRI replacement in next years. - The patented Osram Oslon NP Blue.... it is Signal PC Blue? (LCB CRBP) - no led chips were ever developed for reefing. Deep blue were produced years before people see them on market and thinks to use them in tanks. Those are the basic brick of any white led. They were released to public ONLY when remote phosphor technology became spread - never for reefs. This PC blue is a deep blue with a thin layer of phosphor on adding some extra wavelengths to original 450 nm. Applications, according to datasheet Signaling, Architectural Lighting indoor, Signal and Symbol Luminary. . More than a year ago I proposed to use them in a reef light and people on a forum jumped on my head that I am crazy. To continue the story of famous LEDs for reefing - Lime leds-were designed for street lights, violets for medical and forensic, etc - most modern, good quality leds have a very stable color whatever dimming method is used. Consider same LED as above, there is only 0.002 CX/CY shifts due to current shift, so that argument is rather invalid. Agree, it is like this on very low quality leds. - Lifetime of LEDs - 50k is a no no. For Cree LEDs you may expect 35k (depend by current / chip temperature), where for Luxeons and Osrams can go easily above 100k hours. Lifetime of LEDs have to be specified as T90, T70 or whatever, but LEDs will still burn. They just fade in time. This lifetime number without degrading rate is useless. When you say 50k means 90%, 75% or completely dead?? - I dont get the idea of Cree XBDs unlicensed can be drive at 350 mA and licensed versions at 700 mA, where on datasheet is written 1000mA. You continue this list with Cree XPE and others.... Me, a regular guy can buy ANY LED bin from Cree, Osram, Luxeon or whatever. And again NEVER a chip was designed or patented for aquarium. We are lucky enough that large consumer markets needs specific colors and they push led manufacturers to produce it, otherwise... . It is Friday late evening, time to enjoy my tank and nice weekend.