HPS lights not very efficient after all? by: Anonymous
Thanks, Jason! I just read on another discussion forum that the Sun System 150W HPS grow light uses 408 Watts after 60 minutes of use. (The inital start up was about 600W). This was posted by a distributor of Sun System who tested the light, so I tend to believe it, but I haven't been able to find specs from Sun System. The light is very bright (16,000 lumens), but if the fixture is so hot that I have to keep it far from the plants, it might not be worth it. (I learned that from one of your tips!) So, I'm going to stick with my CFLs for now. Maybe I'll start with lettuce or basil -- I want to grow something! I bought a small fan, but it is too powerful for the 2" passive intake hole that I drilled (the fan moves 80 CFM and I have 7.5 cu. ft!) So, I'm still tweaking. Thanks again for all your help! One way or another I will grow something I can eat!
Mar 16, 2010 Rating
Thank you, Jason! by: Sheila
Wow, what great information! Maybe I need to start this project in November. I do have the window open a bit in that room, and as long as I keep the closet door open a few inches the temperature is about 78 F inside. But I won't be able to leave the door open when I start flowering, and that will probably be when it starts getting hot and sticky outside. I have an A/C in the room but I can't even get the temperature in my apartment down to 80 in the summer. Your idea of separating the lights and the plants with glass is great.
The HPS security lights are also a great suggestion. I noticed that they come in 70W & 100W fixtures, too. Would that be a wiser choice than 150W HPS or my 105W CFLs? This is a subject that confuses me. Should I judge lights by lumens or watts? I thought that HPS lights were more efficient than CFLs, generating more lumens per watt, so I thought I would have a cooler garden by switching to HPS lights. Or is it that CFLs somehow give off more heat per watt than HPS?
Response: Lumens are the measure of light that is actually usable to the plants....so technically, lumens are the measure by which to judge a light. However, when purchasing a grow light, it is safe to assume the majority of the light will be in the usable range for your plants (and so judging your light by watts is also very acceptable). I am not sure if one light puts out more heat per watt than the other. One thing that is certain, though, is that more watts produce more heat.
If I were you, I would give it a go with your 105 W CFL's. The 70 W HPS fixture would be a good choice also. I would be interested in knowing the lumen rating of each, as HPS lights are generally regarded as having a more intense, penetrating light than fluorescents. Either way, your heat problem will still be relatively the same, as the 35 W difference between the two is not that great. Good luck on your project, and Happy Growing!
