400w MH/HPS for 2x2x4 Grow Tent??

Title pretty much says it all. Will a 400w MH/HPS light be too much for my 24"x24"x48" Grow tent? I was looking into some kits on eBay and found some with a cool tube that fit my budget.

My set up would be as follows:

• Carbon filter > cool tube > 6" inline fan
• Passive intake

Let me know what you guys think should I go with a 250w instead?

same setup I'm currently running. It's going to be hard to find a reflector tat fits that tent.

PistilCalyxCola said:

same setup I'm currently running. It's going to be hard to find a reflector tat fits that tent.

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How's the setup working for you so far? Are you in the same size tent as me? Are you experiencing any light burns?

It's still a work in progress. The cooltube looks like it should be easy to cool, I plan to exhaust the heat out my window and have an active intake pumping in fresh air. I plan to LST, with a 400w it's not that likely to have major light burn. 1,000w yeah. I've had my plants under 400w before as close as 0-5 inches with very little light burn, sealed air cooled lights. I bought the small tent on impulse because they were dirt cheap, kinda regret it now though lol

I had a 400w hps w/a 6" cooltube in a 18" x 30" x 35" tent and yeah, it was to much. It bleached some the flowers out and with it on 100%, it raised the temp over the intake air temp. I moved it to a 25" x 35" x 54" with better ventilation, lowered the scrog trellis and it seems to be more comfortable.

jaibyrd7 said:

I had a 400w hps w/a 6" cooltube in a 18" x 30" x 35" tent and yeah, it was to much. It bleached some the flowers out and with it on 100%, it raised the temp over the intake air temp. I moved it to a 25" x 35" x 54" with better ventilation, lowered the scrog trellis and it seems to be more comfortable.

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Do you think a 250 watt would be better? Maybe put out the extra cash for a dimable 400w ballast

I got a 250/400w switchable hps for a 3 x 3 x 6 with 4' can fan air cooled hood and it is still a bit warm in there @ 400w. I will have to either drop to 250w or get a 6' can fan for summer time or it will be too hot. Plus I have even light burned a few of my plants going from 4 bulb 4ft t5 veg light to the 400w hps. So In your situation I would probably go with a 250w. I've used a 250w in the past and still got qp+ yields.

Mine dims 200/300/400. At 200 it only adds 3 degrees. At 300 it adds 8-10. At 400 it soars up to 20-22 degrees with a 6" fan pulling fresh air through. Get the dimmable 400 and turn it down til you can use it.

FlyingHigh025 said:

Title pretty much says it all. Will a 400w MH/HPS light be too much for my 24"x24"x48" Grow tent? I was looking into some kits on eBay and found some with a cool tube that fit my budget.

My set up would be as follows:

• Carbon filter > cool tube > 6" inline fan
• Passive intake

Let me know what you guys think should I go with a 250w instead?

Click to expand...

get a dimmable 600w
given enough cooling a 600 is perfect for that size.
just get an aircooled reflector and a good vortex fan
not to menton it's always a good option in case you decide on a bigger grow later
which inevitably you will
pretty sure the dimmable 600 is nearly the same cost as well

greasemonkeymann said:

get a dimmable 600w
given enough cooling a 600 is perfect for that size.
just get an aircooled reflector and a good vortex fan
not to menton it's always a good option in case you decide on a bigger grow later
which inevitably you will
pretty sure the dimmable 600 is nearly the same cost as well

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What do you think my yield would be in a tent that size with a dimmable 600w? I'm growing a feminized northern lights from Nirvana and plan on building a scrog screen and vegging until the screen is filled. Also plan on lollipopping as soon as I switch to flowering. Also, I really don't want to spend much money so I only plan on a 6in VIVOSUN inline (built in speed controller) with a VIVOSUN carbon filter. That's about all my budget allows for. Will a 6in be strong enough to pull through a cf and a cool tube?

If you put a 600 in a 4x4 space with a 24" deep canopy 2 feet away from the light and that canopy is solid wall to wall, you should pull around 16 oz's. 2x2 is 25% the space, so that's 4 oz's. Your light will take up 8", your pot and underneath canopy will take 18" and you need to be at least a minimum of 12" away from the light. That adds up to 38" of your 48", leaving 10" for canopy. 10" of the 24" we figured the 4 oz's from is about 40%. 40% of 4 oz's would be somewhere between 1.5 and 2 oz's. That's a best case, if everything goes right kinda grow guesstimation on.

PistilCalyxCola said:

It's still a work in progress. The cooltube looks like it should be easy to cool, I plan to exhaust the heat out my window and have an active intake pumping in fresh air. I plan to LST, with a 400w it's not that likely to have major light burn. 1,000w yeah. I've had my plants under 400w before as close as 0-5 inches with very little light burn, sealed air cooled lights. I bought the small tent on impulse because they were dirt cheap, kinda regret it now though lol

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Let me know how that cool tube fits in your tent. Will it be a problem with ducting attached to both sides?

If you shop around for 6" cooltubes, you can find a pretty short one on amazon. The one I found is 19" from tip to tip.

jaibyrd7 said:

If you shop around for 6" cooltubes, you can find a pretty short one on amazon. The one I found is 19" from tip to tip.

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How much space would you say I need between the end of the cool tube and the tent for ducting? I don't want the duct to be smashed and restrict air flow.

FlyingHigh025 said:

How much space would you say I need between the end of the cool tube and the tent for ducting? I don't want the duct to be smashed and restrict air flow.

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I had about 2", maybe 1 1/2", no problem.

jaibyrd7 said:

I had about 2", maybe 1 1/2", no problem.

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Alright that's my plan then

Carbon filter > cool tube > 6 inch inline > exhaust

I also decided on a 400 watt dimmable ballast and keeping it at 50% along with keeping my fan running at medium speed

I plan on keeping the light at 50% so I have more vertical space without burning up my soon to be babies

jaibyrd7 said:

I had about 2", maybe 1 1/2", no problem.

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Wait sorry, I read that wrong. My fan and filter are outside of the tent. I drew air in through 1 end of the tube ( that was 2" away from the tent) and then went straight out the tent through ducting. Try posting a pic so we can see where your tent vents are with where your tube is or will be hanging. I hope this pic shows what I had setup, look at the top.

this one's better for seeing the tube

jaibyrd7 said:

View attachment 3894256 this one's better for seeing the tube

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I'm not able to take pictures right now as I am out of town but I know I have two 4 inch vents in the same location as yours. However, I am going with a passive intake (with only a budget for one 6 inch inline fan) so I need one end of my cool tube to be connect to my carbon filter via ducting which all has to be inside the tent, and the other side to be connected to my fan which will also be inside the tent. I'm really new to growing so excuse me if this is an idiotic question, but how is odor control effective if you are pulling air from outside your tent through your cf, through your cool tube and then exhausted back out your tent? Or do you have another exhaust fan pushing air from inside your tent through your cf which isn't connected to your cool tube? I made a quick blueprint on Microsoft Paint to give you an idea of what I want the setup to be lol

PS: I know the scaling in that is a little off
Also, I found a 17-3/8" cool tube on eBay for $35

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