I'd much rather go over in Lumens, than under...

4x4= 16sqftx5,000L = 80,000Lumens needed.

-Most 600w HPS = 88,000 - 90,000 Lumens
-Most 750W HPS = 110,000 Lumens
-Most 1000W HPS = 130,000 - 140,000 Lumens

So IMHO, I'd go with the 600W as long as my room was a closed in 4x4.
SmokeMyPiece Reviewed by SmokeMyPiece on . Why is there not a 800 Watt HPS system? I need the appropiate system for a 4x4 room. All the online calculators say for my 4X4 room, I need 800 watts. Thats all fine and dandy, but I cannot find a 800 watt system.. I found 400, 600 and 1000.. Is the 600 enough? Or is the 1000 too much? Rating: 5