Tim wrote > I don't see how hydroponics can be certified organic since organic > fertilizers are real no-no's in hydroponics for reasons of sanitation. I don't understand the whole organic thing anyway. Almost everybody thinks "organic produce" is grown without pesticides. Au contraire, mon frere. One can look up the California "organic" regulations easily online. "Organic" produce is treated with "organic" pesticides, some of which have the same neurotoxic mode of action as "non-organic" pesticides. Because many "organic" pesticides are less effective than "non-organic" pesticides, often more must be used. I have this information from California farmers who grow "certified organic" produce for the California market. > ... sodium vapor lamps still give the most bang for the buck, > factoring in initial cost. LEDs have the advantage of low electricity use and very long life expectancy. They can be selected to emit only desired wavelengths so as not to waste electricty on wavelengths the plants don't use. LEDs are far too expensive for most hobbyists now, other than, perhaps, people growing certain crops indoors who don't want the electric company notifying the police about how high the electric bill is, or who don't want to attract police helicopters with infrared scanners flying over their neighborhoods searching for attics that are much warmer than surrounding ones. LEDs will come down in price and I predict serious indoor growers - the ones who care much more about the health of their plants rather than the beauty of the setup - will be using pink and blue LED arrays before long. I have used a high-pressure sodium light on a fixture with a motor that moved it back and forth slowly over the growing area. The bulbs run EXTREMELY hot, dangerously so. A third-degree burn would result immediately from touching a bulb, and it will also probably explode if touched while illuminated, showering extremely hot glass over one's body and plants. Cool bulbs should be handled with gloves, since oils from the hand will burn when the bulb is lit. A little bit of water on the bulb - as might occur if spritzing plants with a water bottle - will also result in an explosion. I had one bulb explode in a winter basement setup for no reason I could determine. The noise was audible upstairs; glass burned many plants and also burned holes in nearby carpet. Had there been drapes there might have been a house fire. If I had children I would never use such lights unless in a room with an automatically closing and locking door. Sodium lights draw a very large amount of electricty, require a special transformer, and are expensive to buy and run. They heat the room they illuminate much more than do fluorescent lights of any design; while perhaps advantageous for some plants, this is not desirable for winter-growing plants. Sodium bulbs also diminish in light output over time and must be replaced regularly. Fluorescent tubes are much less dangerous and work well. Considering explosions and replacing bulbs / tubes yearly or more frequently, I don't believe fluorescents are more expensive in the long run. They are readily available at any shop that carries mundane fixtures. I doubt high-intensity sodium lights will be used for growing plants much longer. Leo Martin Phoenix Arizona USA