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Can any growers tell me about they’re experiences with a 400 watt HID light? How high did you have it from the canopy and what light intensity did you have it at throughout stages of growth? I’m growing four autos in a 5 ft x 2 ft x 3 ft grow tent. I’m in bed and I have in a metal halide bulb which I will be switching to high pressure sodium at flower. As of right now I have my light at 75% 24 in from the canopy seems to be doing okay but I would like it to be optimal…thx
pungolian, rasufa and 2 others5 Comments-
I wouldn’t dim HID bulbs as you lose spectrum as a result of the lower wattage. Lower watts, lower temperature. The gas inside the bulb needs to be at a certain temp to ignite correctly. You can keep both lights about 12-18 inches. Young seedlings and clones can’t handle high intensity while fully established plants can handle much higher intensities. Some plants can handle more light than others so you gotta experiment to find out what they like best. Never try to blast them right out the gate. Always acclimate them to higher intensities over several days. Start at 18 inches and let them grow to it. If they show any stress at any point raise the light a bit. Most plants will do fine with the light 12 inches away in flower under a 400 watt HPS.
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@jmystro thank you that was very helpful!
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I par meter would help you determine your distance. Look up a chart for ppfd during different stages and try to hit those marks by raising and lowering your light. I used to run 1000w HID with no dim. They were often pinned as high as possible and plants grew to them.
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How accurate the app is will depend on the quality of the sensor/phone. They work well with top of the line phones but cheap phones will be far less accurate. They’re useful for measuring differences between numbers at distances but I wouldn’t trust the numbers. I’ve never owned a light meter because I know that reading the plant is a far more important skill. Never let anyone tell you what your min/max ppfd should be for the plant you’re growing unless they gave you the clone and have grown it multiple cycles. Every plant is an individual.
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