400 or 600 - which would you pick?
If my experiments go well (crossing fingers), I hope to grow several (40-80) tomato plants upstairs this winter. I'm trying to decide whether to use 600 watt or 400 watt HID lamps.
Should I go with three 600-watt lamps or four, 400 watts? The former will give we way more lumens (200,000 vs. 152,000) but the cost per lumen is almost the same for both lamps. However, the initial cost difference is significant: four 400-watt systems will cost about $500, three 600-watters about $700. At the same time, growing four plants per 3.5 sq. ft. is going to create a very lush and thick plant canopy. I'm thinking those extra 2133 lumens per s.f. might be worth the extra cost - if each plant produces 3 extra pounds of fruit, I would recoup my costs the first grow.
The heat generated will be about the same and the difference in operating costs will only be about $30 over four months.