400 watt grow questions

Ive currently got six plants in a 5x4 (x6ft tall) under a 400 watt HPS. 2 heavy duty fruity, 2 grand daddy purp, 1 purp kush, 1 pink lady. HDFs are 1.5ft tall, GDP 14-15 inches, purp kush 1ft, pink lady 8.5 inches. Started flowering 3 days ago, showing pistils already after 36 hour dark period. Thinking of adding a second 400 watter to begin rotating 3 sets of three plants 3 weeks apart into flowering. My temp and humidity are perfect, no co2, light held at 12 inches from all plants with no burn. Using a low bloom 1-4-5 fert. flushing each weeks end and slowly upping dose. What kind of yield can I expect on my first six plants I have now with just one 400 watter?? Two 400's?? Is there anything I can do better?

Also 5 gallon pots...

I jus tdid this, last year, this time of year. The one 400 will do ok in your space. adding another 4.. I don't think I would do that. If you throw a 600 you will see a bigger improvement than two 4's. If I were you i'd buy a mover four your 4, then get a six for you bloom room later and put your 4 in you veg giddyup. That will keep you in some nice 5 gallon pots.

I say your current setup with one 400 will be maybe an oz per plant dry, 2-400's..not much different. But the six? That is where you would see the best return, this however opens up a few concerns about heat/humidity.

Bigger pots is a great idea but plan on longer veg time to accomodate. This will bring you your best returns..big plants neeed big rootballs. ( I'll get killed for that from the solo cup crowd).. I just added a 600 dimmable xtreme nano...one word, bada$$.

Two 400 watters will produce you more cannabis than one 600. Dont take everyone on heres advice. Ive run a 600 and a 400 together in a 4x4x7 tent without heat problems but i run cooled hoods.

Now i would totally suggest a 600 over a 400 if you are purchasing a new light as 600s have better penetration. What the guy above me said about one 600 producing more than two 400 is bullshit though.


Its damn near impossible to guess your yield. It varies by strain, environment, skill, ect. My very first grow was under a 400 watt MH 4 plants and i got 3 ounces. The last grow I did with a 600+400 i yielded just about a lb...which coukd have been better but my lnts were too big. My current run has two 600s and im guessing two pounds. I used to have two rooms with total of 14000 watts and i pulled up to 22 lbs from that.......

What im getting at is that it varies even when you have experience. Just be happy with whatever you get.

thanks, definitely eased my mind about getting a second 400w...let u guys know how it turns out

I use a 400W in Veg and a 600W in Flower.... I do wish I had saved the extra $70 and got the 600W for veg.... the 600 in flower gives me rock hard HUGE buds!!
I've heard it argued both ways on here....but I've also done the math...
The 600W setups are actually more efficient if do the math on the watt/lumen output..

While two 400W will give you 800W of lumen power... it is MUCH more energy efficient to go with the 600W
again...this has nothing to do with more cannabis and everything to do with efficiency of your grow..

you WILL get a better yield with the 600...there is no doubt...because of cost effectiveness...
the 2x 400W will be putting out 800W at about the same lumen...
1 600W will keep your energy bill down AND give you the same range of lumen...

Owning both...I certainly would never buy another 400W again...unless I had a mother plant that needed average lighting all to herself....

No disrespect to Shivaskunk...but math does not lie....

I average 8 o's under my 400 hps in 2 gal pots of coco, 4 plants under the light. The biggest thing is the light penetration with a 400 i strip everything under 16-18" from the top of the plant,

a 600W would help with that for sure... much more light penetration.... have you seen the charts posted on the forum?

https://www.rollitup.org/members/sm...s-picture841505-1-distancecharts-20lights.jpg

and

https://www.rollitup.org/attachment...2d1227270612-question-experts-hpsgraphpar.gif

I would definitley be happy with an ounce a plant...just looked at the lumen chart, avg about 6200 lumen per square foot, (62000 total output/10 sq ft), which i am happy about so hoping for more in the two oz per plant range. I just tied the tops off on each plant to start blasting teh small side branches and colas, taking comprehensive pics so i can post the whole grow at once when i am done...thanks fro the help.