light distance from plants?

[Laconfidential427]

I got a 400 watt hps with a inclosed hood and a fan blowing through to keep the hood cool to touch.I have a 6 ladies under the light about a ft some 6 inches from the hood but its cool and not hot at all. Like i can hold my hand on the hood and it is just warm. Can they be that close to the light ? I was told as long as its not hot they can be up against the hood it just means more light is this true or are they to close? sorry for the long story i just wanted to be detailed... thank you for any input!

 

[HippyInEngland]

Hello Laconfidential427

Put your hand at the top of the plants, lower the light until you feel the light is warming your hand.

That is the height you want

eace:

 

[lordhighlama]

If you aren't seeing any signs of heat stress I wouldn't change what you are doing. The closer you can get the light the better off your girls will be!!!

 

[JBonez]

like the above posts, as close as can be is fine.

But at some point there is a deminishing return, thats why i keep my light at least a foot off my plants, they simply wont use that intense light (1000w hps)
without more co2 to support growth. Nutrients factor in here as well.

JB

 

[Laconfidential427]

so co2,,, i just got a set up its 95 % sealed tight but one side i can seal up with a door ima build.As for now i jsut have a sheet of mylar tacked up as a door... how much co2 should i use is my set up ok? what kind of changes need to be made? THANK YOU FORMYOUR INPUT ASWELL

 

[Laconfidential427]

how much co2 should i spray or how often? 5ft. h - 5ft w - 2ft d.. is the size of the box...thankyou!

 

[D3]

You said you have a fan blowing through the light to keep it cool. You should use the fan to draw the air through it, it works much better. I do the same as HippyInEngland for distance, works great. Later Man

 

[JBonez]

You said you have a fan blowing through the light to keep it cool. You should use the fan to draw the air through it, it works much better. I do the same as HippyInEngland for distance, works great. Later Man

this is actually old school of thought, an inlne fan cools the light better with air blowing on it compared to pulling air through the light.

Pulling air is more effective in a box or tent where ventilation is concerned in regards to maintaining negative pressure.

Co2 is not necessary with proper ventilation.

massive yields can and are achieved without the use of co2.