Lighting vs.Grow Area

I have an indoor grow in a 5x5x8 bathroom. I presently use a 400 watt HPS Grolux. I have the ability to raise and lower the light. I currently have 15 plants growing, appear to be lush and 3 feet tall. I took them into flowering 5 days ago. I have been keeping the light 20 inches above the plants and rotate them often in the room. Do I need another light or should this suffice

For perspective, a 1000 watt light will cover a 4x4 well. If I were you id get 2 600 watt lights. 400/25 = 16 watt per sq foot. You should try and shoot for something like 75 w/sqft. After 100w/spft the growth improvement curves off.

That's good advice from GftG. If you can't do 2x600, try at least 1 more 600W in addition to your 400W. Since they're 3 ft. already, the 400W will have trouble penetrating the canopy in a few weeks, 600s can penetrate much deeper...hmmm, now I sound like a porn...

GL!

Thanks for the info. You have any other suggestions feel free to post.

Disagree about your coverage and penetration

here is a chart from a light distributor

MH/HPS Output in Watts .....Primary Coverage Area .....Supplemental Coverage
250 Watt .................................3 X 3 ..............................5 X 5
400 Watt .................................5 X 5 ..............................8 X 8
600 Watt .................................6 X 6 .............................10 X 10
1000 Watt ...............................8 X 8 .............................12 X 12


400 watts is fine for 5x5 and actually 20 inches is to close, you should get a light meter that reads to 10,000 lumens and adjust your lights to hit the canopy with 3000 to 4000 lumens, for stress free plant growth and transpiration

Most growers do not do this so will not advise it to you but if your area is dialed in properly you will see what I'm saying

Actually was given another 400w today and purchased a fluorescent as well. So we'll see how it goes. Great info from all. Any other ideas please post