2 400W HPS. How high does it need to be?

How high should you have a 400W HPS light from your plant?
Just bought two for 120. One is three month old and the other one is comletely new with reflector and inbuilt ballast. =D great deal going to be selling the old hps for the extra cash

umm i would say stick you hand under and leave it there and where ever you hand cant be under the bulb at that height dont put in so close. and 12" i think is regulation on plant to bulb.

It depends on the venting and glass on the light. An air cooled light with tempered glass can be closer than a light without those features. Before I air cooled and added tempered glass to my fixture I kept it 18" above the canopy.

Yeah like he said, with a air or water cooled light then you can go down to as low as 12 inches without any heat issues arising, but if you have like an econowing reflector then keep them like 18 inches above top of plants to avoid stress and heat problems that may be visible.

The reflector is inbuilt with the ballast. It is in like a air cooled reflector. It has a slot where i can slide in a flat cover. I'll take a picture and upload later.

It sounds like it is ready to accept a piece of tempered glass. That would help tremendously.

Ideally you want to keep the bulb 14 inches away from the canopy to achieve 10000 lumens/sqft.

Little Tommy said:

It sounds like it is ready to accept a piece of tempered glass. That would help tremendously.

Click to expand...

Where can i get tempered glass? How much would it be.
Just took some pictures. Going to be up soon.
One ballast with a 400W HPS 3 month bulb. Another inbuilt ballast with a new 400W.
Pretty sweet two ballast for 120. On ebay it was a new 400WHPS KIT for around 150 including the shipping.

The depth of the ballast is 380mm is it alright in a wardrobe with a 450mm depth? 1.8m high.

You can get tempered glass custom cut to your dimensions at any glass shop. That is going to create lots of heat in that cabinet. You may want to air cool the light in addition to adding the tempered glass. Air circulation & heat extraction is going to be key in a cabinet grow.

Are you suggesting a fan blowing directly at it and having like 1inline n outline in the cabinet?