Hey guys I really, really appreciate the great response I have had in this thread. It's great to have so many people pitch in and give me their views.
I'm still really undecided because from the responses I have had in this thread, coupled with my resarch over the past 24 hours there is a lot of conflicting advice out there. Mimicking this thread, when others have asked similar questions some people say the more light the bigger the yield, others say that between 5000 and 8000 lumens per square feet, anything over that is basically a waste of electricity.
Here are some calculations I have been thinking about. Maybe these figures will sway more opinions one way or the other.
600 watt bulb SunMaster = 90,000 lumens
400 watt bulb Grolux = 56,000 lumens
3x3 Secret Jardin Grow Tent = 9 Square Feet
2x2 Tray and Pot Combo = 4 Square Feet
90,000 Lumens / 9 Feet = 10,000 lumens
90,000 Lumens / 4 Feet = 22,500 lumens !!! (surely this is too much?)
56,000 Lumens / 9 Feet = 6,222 lumens
56,000 Lumens / 4 Feet = 14,000 lumens (more than plenty, surely?)
I think what the determining factor here should be is whether you should be counting the actualy grow area or the whole tent/room area. If it's the grow area I should be calculating then the 600 watt bulb will be a waste of electricity as my 2x2 tray and pot combo will be receiving more than double the lumens the sun provides... And even if I settled with the 400 watt bulb my 2x2 tray and pot combo inside the larger tent will be receiving 1.4 times the amount that the sun produces!
Reading online there is a huge discrepancy. There doesn't seem to be a definitive answer to how many watts/lumens per square feet is ideal and at what point the extra light is wasted. I read somewhere that plants basically have microscopic venus flytraps on their leaves that trap single photons and keep them until they have been converted into energy when they open up again. It said that at around 7,500 lumens per square foot the plant can't actually absorb any more light. Then there are others that say anything above 7,500 lumens per square foot and the plant will go into photorespiration which isn't a good thing (not really gone into why that is, but apparently the plant will start using oxygen rather than Co2). Others say that their comprehensive grow books say 2000 lumens minimum and 5000-6000 lumens ideal. Then there are others that claim that they use 1kw lights in 3x3 space and they get good yields. Very confusing! I'm surprised there isn't a definitive answer to this question out there!
Any way just to give you guys an idea of what I will be ordering:
Secret Jardin DR90 Tent
Lumakec Digital Ballast (either 400 or 600 watts)
Euro Reflector Hood
600 Watt SunMaster or 400 Grolux Bulb (Duel Spectrum)
5" Ruck High Powered Fan (365cm3), Acoustic Ducking, Rhino Carbon Filter (includes jubilee clips)
ETI Digital Hydrometer
SMS Fan Controller with Thermostat
500mm (55 watt) Hylite Green Houser Heater
Pair of 7 Inch Clip-on Oscillating Fans
Pair of Bungie Ropes for Fan/Carbon Filter will I need two pairs to hold both filter and fan or just 1 pair??
Pair of Easy Roll Ropes for Ballast
Heat Resistant Metal Tape
pH test strips
59cmx59xm tray that fits 9x6.5litre pots
Plagrom Light Mix
Perlite
Vermiculite
Plant Magic Old Timer Bloom 1l
Plant Magic Old Timer Grow 1l
1 x Scalpel (will reuse)
Clonex 50ml
I'm going to place the order either later on tonight or tomorrow evening after work.
Right now I'm swaying towards the 600 watt dimmable ballast because I doubt I will ever want/need to go under 400 watt of light. This is because about 3 months ago I built a medium size PC Cabinet with two fans and four B22 light fixtures. In this I will be using 4 x 7,500K 11Watt CFLs for mothers, clones and early veg period. The only problem is that it may be a tight fit to keep bonsai mothers and clone/veg at the same time. I can fit 5-6 small pots in there, so I could keep 2 mothers and 4 clones/early vegging girls at the same time so should be fine once I get the perpetual harvest nailed down.
Like I said I will be going SOG. Probably with 2-3 weeks veg and a bi-weekly harvest.
With a 600 watt bulb, plus all the extra watts I think I will be using around 12kw/h per day. With a 400 bulb it should be around 10kw/h per day. Currently I am charged .18 per kw/h so I should be paying £40 a month for 400watt and £60 for 600 watt. Which will be double my current usage (should I be worrying about this pulling up any red flags?)
Huge thanks again guys!
I really hope this thread can help others out there in the future.
