So I got curious and wanted to know what kind of light loss to expect in terms of lux if I went w/ a bargain brand cool tube (Apollo Horticulture) instead of bare bulbs. I know I know, everyone says cool tubes suck, but had to verify it for myself, especially in terms of cooling costs (will explain below).
Okay so I fired up a 600w HPS (also Apollo Hort bargain brand) w/ a lux meter. Let the bulb run about 5 minutes and then took a measurement w/ my meter. I tried to keep the meter at level height w/ the bulb and also about 1 foot away, though obviously there was some variance due to not holding it perfectly in the same spot. Typical measurement was about 660 lux, and the range (as my hand moved ever so slightly) was 620 to 700.
Then waited about a half an hour w/ bulb off, turned the bare bulb on for 5 min, and did the bare bulb test. Typical measurement about 850 lux, with the range about 800 to 900.
Under the most favorable (to the cool tube) measurements (700 vs 800, respectively), the bare bulb was about 14% brighter. Under what I'd call the typical measurement (660 vs 850), the bare bulb was about 29% brighter. Big difference!
My thought was that if the difference weren't so huge, I could envision scenarios in which the extra watts required to keep the room cool w/ bare bulbs could be offset with more light via cool tube. Assuming that it would take at least nearly an extra 100 watts (thinking 14% more power x 600 watts), well, seems pretty simple to just add some more extraction fan power (you can go from roughly 500 cfm to 1000 cfm with an extra 100 watts) and call it a day. So I'm officially convinced, cool tubes blow.
Two caveats: lux is not par -- who knows which part of the spectrum gets blocked by curved glass. And maybe that bargain brand cool tube blocks a lot more light than what else is out there...
Okay so I fired up a 600w HPS (also Apollo Hort bargain brand) w/ a lux meter. Let the bulb run about 5 minutes and then took a measurement w/ my meter. I tried to keep the meter at level height w/ the bulb and also about 1 foot away, though obviously there was some variance due to not holding it perfectly in the same spot. Typical measurement was about 660 lux, and the range (as my hand moved ever so slightly) was 620 to 700.
Then waited about a half an hour w/ bulb off, turned the bare bulb on for 5 min, and did the bare bulb test. Typical measurement about 850 lux, with the range about 800 to 900.
Under the most favorable (to the cool tube) measurements (700 vs 800, respectively), the bare bulb was about 14% brighter. Under what I'd call the typical measurement (660 vs 850), the bare bulb was about 29% brighter. Big difference!
My thought was that if the difference weren't so huge, I could envision scenarios in which the extra watts required to keep the room cool w/ bare bulbs could be offset with more light via cool tube. Assuming that it would take at least nearly an extra 100 watts (thinking 14% more power x 600 watts), well, seems pretty simple to just add some more extraction fan power (you can go from roughly 500 cfm to 1000 cfm with an extra 100 watts) and call it a day. So I'm officially convinced, cool tubes blow.
Two caveats: lux is not par -- who knows which part of the spectrum gets blocked by curved glass. And maybe that bargain brand cool tube blocks a lot more light than what else is out there...