400WHPS vs. 400WMHconversion Which for veg?

[Jman]

In a 34"x34" grow box, which is better? Opinions needed!

 

[cadlakmike1]

MH has a better spectrum for veg. Have you read through the stickies at the top of each section, they are full of tons of useful information, here's a really good resource to get you started.--->http://www.marijuanapassion.com/forum/showthread.php?t=9396

 

[Jman]

Well thank you for the links, beleive me when I tell you I have done plenty of reading, and do understand the spectrum difference. Just looking for some opinions. Ya know, is 50,000 lumens of more red spectrum better than 36,000 of the correct spectrum for veg? Thats all... I mean roughly 9 square feet thats alot of light with the hps could be beneficial....lined with mylar.....think of the possibilities:hubba: mh seems to be hotter than the hps also...

 

[Budking]

the answer is the MH conversion, it puts out much more blue spectrum of light, wich is needed most during the veg stage, i run one my self

 

[BBFan]

Actually JMan, that's a very good question. 6200 lumens of HPS vs. 4500 lumens of MH. 37% more lumens should make a significant difference. I have the opposite set-up- I use a MH ballast with an HPS conversion bulb for flower. I do sacrifice lumens when I switch to HPS. I have read about members here using HPS throughout the grow with good results.
I would say if you haven't already purchased the MH conversion bulb- go with the HPS. My opinion would be that with that many more lumens, it would outweigh the spectrum issues. I don't know if the reverse is true though- ie using MH throughout grow.
Good luck to you and let us know your results.

 

[cadlakmike1]

I personally use a MH conversion for veg and a HPS for flower. Far less lumens are needed when vegging so it is more important to get the correct spectrum. Not to mention the fact that the bulbs you are comparing both provide enough lumens for that space. While the HPS would work the MH will promote shorter, bushier, more compact plants and will help limit the stretch. Again, use the MH conversion for veg and the HPS for flower.

 

[Jman]

That is what I am talking about a little info to bounce around in the old melon....shorter bushier plants is what I want, short nodes...I have seen some girls grown throughout with the hps, and the node spacing looks pretty good to. Decisions, Decissions.

 

[Jman]

My current group of ladies were vegged under 12 4ft verilux flouros. It worked ok until they got about 8" tall then because of week light they really started to stretch..And they are looking lovely. Just trying to keep them tighter..

 

[BBFan]

Then there's always this opinion from Ed Rosenthal:

Marijuana, like all green plants, uses light to fuel photosynthesis. So the more useable light the plants receive, the faster they grow. However, the chloroplasts, little organs in the cell where the process takes place, use the red and blue spectrums most efficiently. They don't use green light and they are fairly inefficient users of yellow and orange light. Unfortunately for plants, both HPS and MH lamps produce most of their light in these spectrums. HPS lamps produce more total useable light than MH lamps. Contrary to what store owners or others will tell you, in controlled experiments HPS lamps outperform either MH lamps alone or mixes of MH and HPS lamps.

 

[Locked]

Good info bbfan...I hve a Mh conversion bulb and a HPS bulb that I hve used in my Auto tent grow.. this was the first time using a MH bulb.. I am more of a HPS fan I think.. I know about the MH for veg HPS for Flowering info but I think you wld do fine with just a HPS bulb...I might gve it a try in a future grow...

 

[Budking]

I personally use a MH conversion for veg and a HPS for flower. Far less lumens are needed when vegging so it is more important to get the correct spectrum. Not to mention the fact that the bulbs you are comparing both provide enough lumens for that space. While the HPS would work the MH will promote shorter, bushier, more compact plants and will help limit the stretch. Again, use the MH conversion for veg and the HPS for flower.

:yeahthat:

i run a 400W MH conversion and have run 1000w conversion. i can get the 400w bulb within 2in of the leaves and its plenty of lumens. ur plants will be denser, lusher, and greener if u can go with a MH. this is just my opinion and from my personal experence

 

[Jman]

I'm glad to see that I have good reason question. Very debateable topic. I set up to use the MH and it seems so much hotter than the HPS...Very white light. Very intense to with the mylar......Gotta monitor temps.. Veg area not very big...Lets see how the girls like it.....Let Ya all know later.Thanks for chimmin in peeps...Maybe I will start a grow journal on this...Anybody interested??????

 

[BBFan]

Personally, I use MH for veg and HPS for flower.

There is much anecdotal evidence out there that suggests using an HPS throughout the grow can cause our girls to be more "leggy." However I have not been able to find much empirical data. I have also read that adding MH lights, because of their higher UVB output, during the last 2 weeks of flower results in more trichome production.:headbang2:

Personally, I'm a big believer in the more lumens the better (to a point).

Good thread JMan- as you can see, there is still much debate on this topic. If costs are not a factor, I would get both bulbs. But that's JMO.