View Full Version : 400w MH for first month of flowering?
11-27-2007, 06:19 AM
Okay, right now i have a 600w HPS which covers a 3 x 3 area. I figure i can fit 6 comfortably. I was wondering... could i double what im doing by getting a 400w metal halide for the first 4 months of flowering then switch to the 600w hps for the the main budding phase. Someone was telling me that plants grow denser with sturdier stems under MH light, and since the first 3 -4 weeks is stretching could MH light help control stretch? Could a 400w MH keep up with 6 medium sized plants for a month in flowering?
11-27-2007, 07:31 AM
11-27-2007, 04:19 PM
a 400w (mounted in a horizontal reflector) will only effectively cover a 2x2 foot square, also a 400w is a less efficient bulb than a 600w if you look at the lumens per watt...it is true that an hps will keep plants stalkier if you are comparing lights with the same watts, with a 400w in a 3x3 foot space the plants might actually stretch more since the light is weaker than the light that should be in there..they will be stretching to the light
11-27-2007, 07:56 PM
What about a 600w MH. I was considering buying a digi ballast. Would the blue spec. for the first 3 weeks (main stretch) maybe make the internodes tighter and the stems sturdier before the buds really start getting big? And woul having them side by side make it more full spectrum?
11-27-2007, 11:12 PM
if you can find a 600w MH bulb, they are pretty rare but I believe there is a conversion available, and still you will need to see if your digi ballast is compatible with the MH bulb (european and japanese bulbs probably work, usa bulbs)???
might be easier to get a separate 400w MH bulb and ballast and run both for the first 3 weeks...more light intensity = less stretch (usually)
02-24-2008, 10:24 PM
rule of thumb is 50w per light under MH for veg and 80w per light for flower HPS. therefore for 6 plants the 400w MH would be ideal. you can have a mag kit wired 110v or 120v in the usa. i paid 145.00 without bulb for mine, this is complete. you can run a 400w 18" from the plants without heat stress and a 600w - 2' from the tops. with sheilding both can be lowered to inches from the tops. i have set up medical grows for people with these 2 ballasts.
a MH 400w will veg 8 plants nicely and then transfer 6 or 7 to go under a 600w HPS to flower; keeping 1 or 2 back for clone moms. you can get the 600w MH in europe but not so far in north america although i know some who have them. most peeps i know who want the same wattage as a 600w HPS run a combo 400w and 250w MH. hope this helps. indicas usually triple in height therefore you trip when veg height is correct. e.g. 12" veg = 36" flower. and by bringing your HPS down will limit stretch.
03-09-2008, 04:18 PM
use the 600w HPS for flower and then ADD the 400w MH for the last 4 weeks.
06-30-2008, 05:25 PM
Hi all, as i recall weed grow under Mh(hpq i in my case philips)does need no curing buds are much more airy but much more oily than using HPS(grolux in my case)where dense and hard but they didnt have no where near good hit as Mh weed ,so combination of lamps whould be great like on every 600w hps goes one 400mh trough whole grow .u fellas agree?
06-30-2008, 05:56 PM
Use a 6400K type lamp for the first decade of days of flowering reduce stretch, yes.
But if you use it for a month, you will produce more leafs than flowers and it's not very wanted if you don't want produce only bubble with your plants for example.
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