MidnightJoker
Well-Known Member
Can someone please tell me the correct distance a 400w MH lamp should be from the canopy of 8 day old seedlings? I think it's supposed to be 18" but I could use a second or third opinion. Thanks.
Lighting Question
- Thread starter MidnightJoker
- Start date
MidnightJoker
Well-Known Member
I hope I am reading this correctly. My 400w MH lamp should be at 13" from the canopy?
MidnightJoker
Well-Known Member
That's what I was thinking, Encomium. I currently have the lights at 18"...Do you think this is a good height to start off with?
Encomium
Active Member
I just looked at your recent journal post and I'm struggling to believe that it's solely a lighting issue since a 400 watt MH is more than enough light even at your initial height of 36 inches. Heck my girls when I started them grew just fine with a 250 watt MH and I had them started the first week at about 30 inches from the light source.
To answer your question however, I think 18 inches should be just fine for seedlings and you could lower the lights each day by a small amount.
To answer your question however, I think 18 inches should be just fine for seedlings and you could lower the lights each day by a small amount.
MidnightJoker
Well-Known Member
When my girls were in the root cube, I did not have them under my 400w MH lamp. I just had them under a regular lamp, and I was getting stretching so I transplanted them today to go under the 400w MH.
Encomium
Active Member
Ahh I understand now. Well I started my seedlings off with a 250 mh @ 2 feet with tight internodes and vigorous growth but had them on 24 hours/day.
I think most growers consider this period (usually applied to transplanted clones) as a "hardening" period because you want to have your girls adjust to HID lighting. I'd raise your lights to 2 feet at least for the first 2-3 days and then start lowering them a bit each day.
I think most growers consider this period (usually applied to transplanted clones) as a "hardening" period because you want to have your girls adjust to HID lighting. I'd raise your lights to 2 feet at least for the first 2-3 days and then start lowering them a bit each day.
BigGMoney
Member
Be oh so careful with hotspots and 400w and seedlings...I agree with the above, without question.
Start them higher than 18", and lower CAREFULLY...seedlings are lil babies, so they need TLC
Encomium
Active Member
Also, vegging MJ isn't as light greedy as flowering MJ is. I'd only worry about getting the full amount of PAR levels during flowering and even then you should be wary about hotspots like BGM states.
PS - You happen to get a light diffuser for your bulbs Midnight?
total bull shit, I've sprouted seedlings outdoors full summer sun and they thrived, 4 nodes in less than 3 weeks.
MidnightJoker
Well-Known Member
OK, so I raised the lights to 24" to start with. Then over the next few days I will lower them slowly until I reach 18". Thanks.
No, I didn't get a light diffuser with my set-up. Could you please tell me what that is exactly, and maybe where I could pick one up?
Encomium
Active Member
Mmm well I picked my diffuser up (called "Super-Spreader" by Adjust a Wing) when I purchased my reflector. I've seen brands like the S-Spreader that don't require the Adjust a Wing reflector but am unsure what they are called.
The diffuser basically removes the hot spots directly beneath your bulb and allows you to move your light down lower to your canopy. Here is a link to the one I purchased so you can get an idea of what it is.
I'd say they aren't integral to your set up especially during veg but in flowering it may help so you don't burn your plants directly below the lights.
Edit: You know on second thought I remembered you got an exhausted reflector/light combo that probably has a glass right below your bulb. I got mine partially because the bulb was bare on the reflector I bought so I thought it would help. Plus the gimmicky website pulled me in.
The diffuser basically removes the hot spots directly beneath your bulb and allows you to move your light down lower to your canopy. Here is a link to the one I purchased so you can get an idea of what it is.
I'd say they aren't integral to your set up especially during veg but in flowering it may help so you don't burn your plants directly below the lights.
Edit: You know on second thought I remembered you got an exhausted reflector/light combo that probably has a glass right below your bulb. I got mine partially because the bulb was bare on the reflector I bought so I thought it would help. Plus the gimmicky website pulled me in.
MidnightJoker
Well-Known Member
Actually, I don't have a cool tube on my light, just the bare bulb so this is fantastic. I didn't even know these existed! I am going to order one so that I can get my lights right on the canopy. Thanks, man.
BigGMoney
Member
Nice! I agree, started outdoors, they are very hardy plants.
But indoors, once they are started there, cannot just go directly from inside to outside, even if they are more mature. Lighting becomes important, because unlike outside, your lights can BURN your plants.
Sure is a great thing that sun is further away or we would all burn up.
BigGMoney
Member
Cool tubes are the answer...you can put those babies so close to the light! Check around for the thread that show the 400w cool tube standing vertical in the grow room. Very impressive!