Running 400w MH@ 75% during Veg? Anything wrong with that?

JanesRain

JanesRain

Well-Known Member
My tent gets super hot if I run this 400w MH at 100%, so I run it at 75% (300w). Will my plants still do good at 75%?

I am getting another fan soon to keep the tent cooler. Plants only on the first 2-3 weeks of veg stage.

At what point should I turn it up? I also have my HPS bulb for when they're ready to flower.

Thanks
 
$bkbbudz$

$bkbbudz$

Well-Known Member
Welcome to RIU, and the wonderful world of cultivating the world's most misunderstood and feared medicines!!!

The only 'advice' I can give you or anyone is to read and learn and then apply what you have read and learned to your garden and you cannot fail. Anyways, remember the search tool is your friend...Lots of folks here willing to help a new farmer get up and growing. But at the end of the day your grow will be only as good as the knowledge and work you put into it.

It is always great to ask questions but do not take anyone's advice or opinions and follow blindly. Do your own research, you will be much happier knowing you have done it for yourself and by yourself. The first buzz you get from your own budz...is by far the BEST high you will ever have!

Do a search using your current question as the keyword(s) and ZOOOM!! Like Wonka's Great Glass Elevator…off you go to tons of threads answering all your questions. Read all the Newbie Central stickies and learn…

Soaking up all that information and sifting through it, is going to take time. You will likely finish your first grow by then. Viola! grow complete and education well under way.


JanesRain said:
My tent gets super hot if I run this 400w MH at 100%, so I run it at 75% (300w). Will my plants still do good at 75%?

I am getting another fan soon to keep the tent cooler. Plants only on the first 2-3 weeks of veg stage.

At what point should I turn it up? I also have my HPS bulb for when they're ready to flower.

Thanks
Click to expand...
The issue at hand should not be is dimming my HID ok? Rather, how can I cool 400w HID in my tent and properly ventilate it?

You got pics of your tent and the area you have it in??
 
sworth

sworth

Well-Known Member
An air cooled hood..tubes are cheap...and at 400w you can pull through the carbon filter with the same fan
I reckons anywaze...(:
 
JanesRain

JanesRain

Well-Known Member
sworth said:
An air cooled hood..tubes are cheap...and at 400w you can pull through the carbon filter with the same fan
I reckons anywaze...(:
Click to expand...

Well, to save money on my electric bill I just keep the door open and my tent doesn't get above 84 degrees, and I will run the carbon filter/fan when they start to stink. Was mainly just wondering if my plants would grow any differently running the bulb at 75%. I can always run it at 100% if not.
 
JanesRain

JanesRain

Well-Known Member
$bkbbudz$ said:
The issue at hand should not be is dimming my HID ok? Rather, how can I cool 400w HID in my tent and properly ventilate it?

You got pics of your tent and the area you have it in??
Click to expand...

I couldn't find a lot about dimming 400w's, so I asked here. Figure somebody would know. Yep here's a pic :)

KIMG0212.jpeg
 
$bkbbudz$

$bkbbudz$

Well-Known Member
First...you spent some $$$ on a nice fan...use it too it's full capacity and get a cool tube. 2nd..way too many plants for that size tent my friend. More plants does not necessarily mean bigger yield.
 
$bkbbudz$

$bkbbudz$

Well-Known Member
I have 400w HID with cool tube and a 260cfm can fan. I can have the tent closed with this set-up and temps have never been above 85 degrees F

cool tube2.jpg

cool tube1.jpg
 
JanesRain

JanesRain

Well-Known Member
$bkbbudz$ said:
First...you spent some $$$ on a nice fan...use it too it's full capacity and get a cool tube. 2nd..way too many plants for that size tent my friend. More plants does not necessarily mean bigger yield.
Click to expand...

Not really. 4 of them are Dwarfs, which won't get very big, and the rest are also small size auto flowers. The 2 in the cup a micro grow. I don't think it's too many
 
Jimmy Sparkle

Jimmy Sparkle

Well-Known Member
I run a 400 watt in my 4x4x6 plywood grow room and in my opinion even in a space this small 400 is at the low end of acceptable power for this area. Dimming a 400 just seems pointless, things will grow but at only a fraction of what it could have been. I've got a very large cfm exhaust fan dialed in on a rheostat. It gets hot outside I turn it up. I never get above 80 degrees . I would increase ventilation before I dim power.
 
JanesRain

JanesRain

Well-Known Member
KIMG0214.jpeg KIMG0193(1).jpeg
Jimmy Sparkle said:
I run a 400 watt in my 4x4x6 plywood grow room and in my opinion even in a space this small 400 is at the low end of acceptable power for this area. Dimming a 400 just seems pointless, things will grow but at only a fraction of what it could have been. I've got a very large cfm exhaust fan dialed in on a rheostat. It gets hot outside I turn it up. I never get above 80 degrees . I would increase ventilation before I dim power.
Click to expand...

I have seen a major increase in growth since switching to this 400w. I was using a 300w led that was just horribly bad for growth. Check the difference in just 4 days . They Def like it, but I will turn to 100% if they seem too slow
 
JanesRain

JanesRain

Well-Known Member
ttystikk said:
Running MH at anything other than its recommended setting will dramatically shorten its lifespan. This goes for any HID, MH is just a lot more sensitive to it.
Click to expand...

Source? Couldn't find a lot about that. Seems that if the company that provided the bulbs also sent a ballast, they should work fine together without damage, no?
 
astronautrob

astronautrob

Well-Known Member
Running the bulb at 75% is going to change the spectrum, probably still be fine for right now but 100% would be better. I used to veg with a 400w MH and would bring it down to 50% when they were seedlings for a short time but no longer than was needed you generally want it at 100% if you can

I'd just get a hood or cool tube, I mean you already have the fan....
 
$bkbbudz$

$bkbbudz$

Well-Known Member
JanesRain said:
Nice setup :). I'm running my exhaust fan on low power and it's keeping the tent @ around 84 degrees and 30% humidity. I imagine I'll need to run it on full(or close to it) and my HPS on 100% once these girls start flowering :)
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ok, you said you cannot close the door because of excessive heat. IMHO it is optimal to keep the door closed in a tent grow. It helps light reflectivity and encloses the garden as it's own little eco-system.

Bottom line here is... if you want to max the potential of your tent and light...you need an air-cooled hood and to use 100% of the 400w available to you. Does that help?
 
JanesRain

JanesRain

Well-Known Member
$bkbbudz$ said:
ok, you said you cannot close the door because of excessive heat. IMHO it is optimal to keep the door closed in a tent grow. It helps light reflectivity and encloses the garden as it's own little eco-system.

Bottom line here is... if you want to max the potential of your tent and light...you need an air-cooled hood and to use 100% of the 400w available to you. Does that help?
Click to expand...

I meant I'd prefer to leave it open and not run the fan, but yes thank you. I'm keeping it closed now with the exhaust fan on. Constant 82-84, could probably bring it down to 80 if I ran the exhaust at 100%, but that thing is loud as fuck
 
$bkbbudz$

$bkbbudz$

Well-Known Member
JanesRain said:
My tent gets super hot if I run this 400w MH at 100%, so I run it at 75% (300w). Will my plants still do good at 75%?

I am getting another fan soon to keep the tent cooler. Plants only on the first 2-3 weeks of veg stage.

At what point should I turn it up? I also have my HPS bulb for when they're ready to flower.

Thanks
Click to expand...
JanesRain said:
I meant I'd prefer to leave it open and not run the fan, but yes thank you. I'm keeping it closed now with the exhaust fan on. Constant 82-84, could probably bring it down to 80 if I ran the exhaust at 100%, but that thing is loud as fuck
Click to expand...
HUHHHH??? Your OP said you are diming because the temps in the tent are "super hot" Now you say the temps are in a range you are accepting of. If you are happy with the temps why dim the light at all...something ain't adding up just right here...Smells kinda ..fishy.jpg
 
JanesRain

JanesRain

Well-Known Member
$bkbbudz$ said:
HUHHHH??? Your OP said you are diming because the temps in the tent are "super hot" Now you say the temps are in a range you are accepting of. If you are happy with the temps why dim the light at all...something ain't adding up just right here...Smells kinda ..View attachment 3688515
Click to expand...

No need for the mental masturbation. Tent running @ 100% gets into the mid 90s without exhaust on and door open. WIth exhaust on @ 100% it hits about 87-89.

Just trying to save electricity ^_^, but I am running 75% with exhaust on medium low w/ tent closed

Thanks for all your help, fellas.
 
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