Let me start by saying I have had many many years of experience growing cannabis and have thus far produced over 100 batches in several locations many at the same time, so believe me when I say there is very good reason not go for 600w sodium blubs you will get nowhere near the amount you can get if you use 1000 watt sodium bulbs and that is a fact.
In the old days you had to use 600 watt bulbs because of heat issues but this all changed when air cooled lighting became available. I personally started using air cooled lights before they were even available as I made my own version of an air cooled light long ago before the 1000 watt bulbs even gave out the kind of lumen output they give today.
Nowadays 600 watt bulbs put out an output of up to around 90,000 lumens, 1000 bulbs put out up to around 160,000 lumens. The question is how much difference do all these lumens make? The simple answer is A LOT in fact your yield could increase by as much as double due to not just the extra lumens but also the deeper penetration from the extra power meaning less under developed buds at the bottom of plants that often end up in the bin.
Now for all you eggheads let me explain the mathematics/science behind why more lumens results in far bigger yields.
First you must make sure the coverage of your plants is right. Ideally you should not be able to see the floor if looking down on your plants. Secondly you must use the correct food including EC levels and nutrients etc. then there is a formula you can use to work out the yield you can expect. You get 0.00001 gram per lumen per hour of light so to calculate the yield of a 600w or 1000w bulb you must do the following equation:
600 watt bulb
90,000 (Lumens) X 0.00001 (grams) X 12 (hours) X 60 (days) = 648 Grams per light
1000 Watt Bulb
160,000 (Lumens) X 0.00001 (grams) X 12 (hours) X 60 (days) = 1152 Grams per light
Results will vary from plant to plant and there are many factors other than just lights to take into consideration, but under optimum conditions the above amounts are what you can expect. Below I have made a graph to give an idea of the difference based on several different set up’s with optimum conditions. This graph does not reflect the extra you can also get from the 1000w bulbs from extra penetration so for the 1000w bulbs the results can be even higher.
2 X 600 Watt Bulbs = 1,296 Grams
2 X 1000 Watt Bulbs = 2,304 Grams
3 X 600 Watt Bulbs = 1,944 Grams
3 X 1000 Watt Bulbs = 3,456 Grams
4 X 600 Watt Bulbs = 2,592 Grams
4 X 1000 Watt Bulbs = 4,608 Grams
5 X 600 Watt Bulbs = 3,240Grams
5 X 1000 Watt Bulbs = 5,760 Grams
6 X 600 Watt Bulbs = 3,888 Grams
6 X 1000 Watt Bulbs = 6,912 Grams
7 X 600 Watt Bulbs = 4,536 Grams
7 X 1000 Watt Bulbs = 8,064 Grams
8 X 600 Watt Bulbs = 5,184 Grams
8 X 1000 Watt Bulbs = 9,216 Grams
9 X 600 Watt Bulbs = 5,832 Grams
9 X 1000 Watt Bulbs = 10,368 Grams
10 X 600 Watt Bulbs = 6,480 Grams
10 X 1000 Watt Bulbs = 11,520 Grams
