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400w or 600w for veg?

Thread starter #1
Hi all, I have both a 400w and a 600w HID ballast. I'm starting my next grow and am wondering whether I should veg with the 400w and flower with the 600w, or just do the 600w all the way through. The only reason I'm debating it, is because I'd like to save a buck or two in electricity ($.23/kw!). But I don't want to save a buck if I'm going to short myself on the grow.

My setup is a 5 bucket, 4 plant RDWC, in a 4x4x7' tent. It will be my 2nd grow with this setup.

Thanks for any advice!

Fuzzy Duck

Well-Known Member
I use a 125w giant cfl E40 fitting 6400k bulb for veg but i use a very small veg area of 60cm by 60cm for 3 to 4 plants on average.. but that is soil/compost grow by the way where equipment is smaller...

Then flower under a 400w HPS or dual spectrum bulb in a larger tent of 90 cm by 90cm, i've used both for flowering but not at the same time !

Ultimately in veg the real saving is choice of bulb cfl or T5/8 tubes of 6400k/6500k will be cheaper to run than a MH counter part & will give suitable veg growth... :thumb:

But what some say on X wattage etc per square foot for cfl/T5,8 tubes etc is slightly not true with more research needed ! all i say is don't use domestic bulb crap and go for pro bulbs :high-five:

Its a 2 side coin thing really...

More likely a maths & results ratio.

But a 600w is better for flowering than a 400w & even 1000w bulb once you look at things in detail...

Oh ye size of plant may effect yield & this may include total veg time plus stretch factor of strain grown to given height of grow area, so that is a bit more to think about :Namaste:
Thread starter #3
Thanks buddy, buying more lights would cost me more than I'd spend in electricity. So I'll stick with what I've got. I have hortilux bulbs for both ballasts. MH and HPS.
I am wondering what kind of growth difference would I get using the 400w ballast/bulb for veg instead of the 600w. I have very good ventilation and can keep the bulbs close to the plants. Since there's not as much plant to absorb the light, and I can keep the light close, would I see a difference? Obviously I'd use the 600w for flowering.


Fuzzy Duck

Well-Known Member
400w vs 600w MH is not going to make much of a differnce in veg to be honest as most hydro system result in faster growth.

How ever size of light foot print to area coverage to suitable wattage per square foot does.

400w will cover up to 1 m2

600w will cover up to 1.2 m2

Or divide wattage by total square foot of area to work out wattage per foot.

Ideallyy you want...

50w per square foot average.

65w per square foot is optimal..

25w and lower is pretty poor.
Thread starter #5
Thanks fuzzy! That is very helpful. By those numbers I'm short no matter what lol. I pulled about 10oz off 4 plants in my last grow.

Fuzzy Duck

Well-Known Member
I believe you can do better :)

It may be hanging height at question ? er like inverse square law of light effect, diminishing light return over distance for example & this may help a little if so the case ?

I believe that is for standard reflectors as air cooled hoods/reflectors can be hung lower but reduces light foot print...

Yield may also be strain related even but it may increase with super cropping methods such as LST, Topping etc

But topping may increase veg period by a few weeks for suitable regen growth to take place !
Thread starter #7
Thanks fuzzy, I do have am air cooled hood, which is exhausted through an 8' vent, with an inline fan.
I topped 3 and it took forever to rebound. The one I didn't top appeared to grow about the same amount of bud as the other 3, go figure. I might lst down the road, but this time I'm not going to top or anything. Flowering took forever and the crystals never turned past white. One plant looked like it was dying of old age, so I harvested them all. The smoke is great. I grew 3 critical kush and one blue og. The blue og is the one that every leave, including the flower leaf, died. I've grown outdoors in the past and never saw a plant look like that. Though when I grow outdoors, bud rot usually dictates harvest.
I used that light table. It's a great tool!
Thread starter #8
That was under a 400w veg and 600w for flowering. The 600w what a gift from my wife who doesn't even smoke. I'm a lucky guy :)
Next up is cotton candy. The rdwc was cleaned the other day and is running a bleach/water solution as we speak. I plan to germinate the seeds tomorrow. What a fun hobby!

Fuzzy Duck

Well-Known Member
Mmm when topping you need a few weeks to recover or more for suitable regenerative growth to take place & normally lengthens the veg period a bit to increase the yield !

Flowering time may depend on strain grown as their can a good few weeks between indica dominate too sativa dominate & hybrid strains, so knowing expected flowering time may help a lot to said ripening or expected time of harvest...

How ever the mention of white crystals, one would assume trichome development & that is the stuff which makes the bud look sugar coated :high-five:

When the trichomes (mushroom shaped crystals on bud once viewed under a scope) all appear near 100% cloudy/milky & that being the peak THC content of plant/strain grown & once the trichomes change colour to amber/orange the THC degrades !
Thread starter #10
Thanks fuzzy. I thought I wanted all milky with a few amber/dark colored trichs mixed in.
Or did I have all clear trichs with a few milky trichs mixed in?
LMAO I'm so stoned I can't remember!!
Hey I had that same issue, I resolved that with a purchase of a Solis Tek system. It is a 400,600,and 1000 watt. You really want to check this out. We have 12 of these that produced 28 pounds of Chemdawg Well worth the cost.:cheer: