Most HID lamps use about 75% of there watts to get up to illumination temp. Lumens are more the light intensity the lamp produces and par watts are the number of watts that the plants acually use. 1500 lumens per square foot is the average intensity growers are told to use from my reading. The dull side of tin foil is not to bad but mirror like surfaces absorb the light. Mylar is easy to come by at any grow shop. You can order it online at ww.wormsway.com but they are not open today, as I tryed calling them when I woke up. Personally I prefer flat white paint.

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karmaxul Reviewed by karmaxul on . Watts or Lumens? How do you guys mesure the amount of lighting? Is it whatts or lumens? and about how many of (either) would you need to support 14 plants? Dose anybody know where to obtain mylar in the US? or are there any other reflective materials here in the USA that work well? I know tinfoil is a nono. thanks for any info! I really appreciate all the help! Rating: 5