New Grower 400w HPS distance from plants

[Think]

Hello! I'm doing a second grow but it's my first for indoor, I'm going to have 3 AutoXtreme's! what is the distance I should have with a 400w HPS at seedling stage veg stage and full flower?

If someone can help me that would be wicked!

Cheers Mr Think-Different

 

[botlowsky]

Hello!

I use 60-70cm in the for the seedlings, 40-50cm in veg, and closer as you can in the flo.
For me it works. Use cooltube it helps a lot to decrease the distance.
All you need to carefull with the seedlings. 400W can make heat.
Maybe its help:

 

[Think]

Hello!

I use 60-70cm in the for the seedlings, 40-50cm in veg, and closer as you can in the flo.
For me it works. Use cooltube it helps a lot to decrease the distance.
All you need to carefull with the seedlings. 400W can make heat.
Maybe its help:

View attachment 337485

Okay sweet, thank you! I haven't got the money for a cool tube but will a fan blowing in line with the light cool it down?

 

[dude]

Okay sweet, thank you! I haven't got the money for a cool tube but will a fan blowing in line with the light cool it down?

Yes.

I just hold my hand there for a few seconds check the heat.

I have a 400 also and have just removed the reflector and hung it vertical which has allowed it to be closer to the plants

 

[Son of Hobbes]

Okay sweet, thank you! I haven't got the money for a cool tube but will a fan blowing in line with the light cool it down?

A fan blowing on the light may move some of the heat away from the fixture, but that won't do anything to increase the extraction rate of the hot air being pulled out of your grow space. Fans do not cool air. Fans move air. Air in motion removes heat from your body faster than air not in motion; combine that with water evaporating from your skin and you feel a "cooling effect."

Those lights generate quite a bit of heat; what is your temperature outside of the grow space (are you using passive air intake or active air intake?) What are you temperatures inside the space with the lights off? What are your temperatures in the space with the lights on?

What is the size of your space and what are you using for extraction fans?

One thing you can do, if you have the lights and the grow space but haven't germinated yet; you can try some dry runs with the light. Let the light run for an 18 hour cycle and monitor the temps at various times of the day. Spring's coming and summer will be here soon; so take into consideration the potential increase in temperature in your area. Remember, there's usually a pretty good temperature shift at dusk and into the evening, if you find your space gets pretty hot in summer months; you can try to run your lights on more in the evening than in the day to help with the cooling effect.

Some great points made by these other fellas; a good test is the "back of your hand" test, where you put the back of your hand at the top level of the plants and hold it there for a few seconds. If it's uncomfortably warm, it's too warm for the plants. If you want to experiment with how much of a difference it makes, stick your hand under it at 12 inches and test it, then start raising it in 2 inch increments. Should be able to correlate real quick how much is too much. HPS/MH can burn seedlings if you're not careful, that's why it's better to keep them raised up higher than you normally would in veg/bloom. If you spend some time with your seedlings, you'll start to see how they react to different light distances (less stretch, more stretch.)

Just my "My 2 cents" Great information everyone!

 

[botlowsky]

Yes.

I just hold my hand there for a few seconds check the heat.

I have a 400 also and have just removed the reflector and hung it vertical which has allowed it to be closer to the plants

My experience tell me a simple fan can help, but cooltube is the ideal choice.
When I use 250W HPS bulb, and I dont have a cooltube I use a fan to. It help, but 400W can be really heat.
When 400W produce 28-30C in my box with a fan, but when I buy a cooltube its around 24-25C.

 

[dude]

My experience tell me a simple fan can help, but cooltube is the ideal choice.
When I use 250W HPS bulb, and I dont have a cooltube I use a fan to. It help, but 400W can be really heat.
When 400W produce 28-30C in my box with a fan, but when I buy a cooltube its around 24-25C.

Seems reasonable, don't cooltubes have extraction attached/needed?

I was just answering that a fan at the bulb will keep it cool. I presumed that he has extraction of the air.

As I keep saying to people (sorry lol) I've taken off the reflector and the heat has dropped a couple of degrees any way.