From the link you provided to the HTG Supply website:
Outstanding Reflective Qualities: 95% effecient!
- Amazing uniformity in light spread
- 10% more light on the plant canopy.
- Reduces green house / grow room shadowing and "hot spots"
- The light distribution compared with a well designed luminaire/reflector is superior giving an effective higher light output.
- No heavy, expensive shades/reflectors to assemble.
- High Output 58,000 LUMENS! (standard 400w HPS bulbs emit only 50,000 lumens)
- Higher Output = Faster/More Plant Growth = Higher Yields
- Universal positioning - Longer Life than standard HPS bulbs (24,000+ hours)
- Can be used inside the Cool Tubes - Color Temp: 2100K
- One Year Warranty
My problem with these statements begins with that they continue to advertise the lamps values in lumens not PPF. After that it seems to me they are stating they can create more lumens by adding a reflector. Lumen measurements taken in an integrating sphere would be light emitted in all directions. If the reflector aims light which presumes proper lamp orientation in the socket and you don't have this lamp inside a housing where a reflector could be installed for a fraction of the price you are undoubtedly purchasing this lamp because you believe the advertising that the internal reflector has increased lumen output. Not only is this patently untrue the reading they should be advertising would be an 'in situ' measurement whereby the candela plot takes into consideration the reflector optics as if this were a lamp/fixture measurement which brings us back to a PPFD value in plant lighting vernacular or as they persist in stating photopic values you would be interested in a candela plot where Lux/Footcandles values are stated.
As I said earlier, save your money and put in a good external reflector. The value of a reflector within the lamp is, to be kind; 'misunderstood' by those who would market them for benefits that would go beyond those of a high quality, well designed external reflector.
The light distribution compared with a well designed luminaire/reflector is superior giving an effective higher light output.
But then they make this statement and I know they are selling lamp hype not reality.