[Blunt Africa]

Hi there

I'm gonna be getting myself a 400W HPS soon and see that you have 2 types of globes available, elliptical or tubular.

I currently have a 70W Elliptical HPS which looks like a conventional pearl frosted bulb. From what I can see the tubular bulb uses clear glass.

My question is if there are any real differences between these two bulbs in terms of effectiveness, heat etc...

Which of the two do you think is best, but more importantly "why?"

l8r

BA

The coated bulb emits less lumens than the other bulb, thats the only major difference...

[pontiac]

HPS bulbs (250w and above) are almost always tubular. Metal halide bulbs are fat and eleptical (some horticulture companies make them tubular). There is no difference between the two, in terms of performance, and heat output. However, the eliptical types wont fit in many reflectors and cool tubes, theyre just too fat.

[Blunt Africa]

Thanks for the responses there. I have access to both types of bulbs here in Johannesburg, and the elliptical 400W bulb is a real fatty!!!

I can see the argument for the tubular.

Now what about the effectiveness of the 400W bulb? How far down the canopy will it be able to penetrate?

Also what distances are you guys growing between the bulb and the top of the plants?

[pontiac]

Ahh good thing you've asked that, i have a chart that you might find useful:

[Blunt Africa]

Thanks Pontiac, great info there.

So it looks like a 400W will give about 15 inches of penetration down the plant if the light is situated 6 inches from the bulb. Obviously heatburn may be an issue if I have my girls that close to the bulb.... any thoughts son that?

[bostrom155]

Cool tube it, minr can get with in a few inches but light burn is an issue then.

[pontiac]

In my opinion 6" is a bit too close to plants for a 400w, even with air cooling. You should keem the light no closer than 12".

[bostrom155]

Originally Posted by pontiac

In my opinion 6" is a bit too close to plants for a 400w, even with air cooling. You should keem the light no closer than 12".

I'm at 6-14" total and always keep an eye for light burn

[Blunt Africa]

Hey Bostrom

Nice cooltube you got there.

What size room are u growing in there and how does the tube affect temps?

Also could I do a cool tube or something similar with a Prolite reflector (This is what I'm thinking of getting.