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400w or 250w What would you Have

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patch View Drop Down
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  Quote patch Quote  Post ReplyReply Direct Link To This Post Topic: 400w or 250w What would you Have
    Posted: 07 July 2009 at 23:24
Hay all, %3c3cmoke%3c20eye
Going to make the switch next grow to a higher output ballast, etc,

And wish to know with my diamentions what you would choose?

The grow room i made is "1200mm x 700mm x 2200mm" L/w/H, and i have the 150w and normally just 4 plants,

This last few weeks in the uk have been HOT and i struggle to get temp's below 29c its been getting over 30 if i close the doors's to the room,
For extraction i have a 30ltr a min inlet fan from a window and 30ltr outlet at top there's also a small fan blowing between the plant tops and Light!

Worried a 400w will create that much more heat it'll frazzle the plants,
Is a cooltube the way forward?

Any suggestion's are considered %3c3cuch

P.s. I like the mantis pro reflector and the Powerplant Daylite hps Ballast 250 / 400
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  Quote Solidopc Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2009 at 00:16
400watt all the way. Even if you need a larger fan. I use a 150mm extractor, and granted, with the heat we've had lately, it aint keeping them optimul, but it is around 30 celius at worst. You get cracking yields from a 400 in your sort of space, jumping up only 100watts on a new lamp just doesn't seem worth it to me. You'll allways wish you had a larger one in the end, so save yourself the money.
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  Quote patch Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2009 at 23:16
Ok good shout, have to buy more fans then :(

Altho temps have been fine since that heat wave passed,
Is 30celius ok long term or to hot?
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  Quote Solidopc Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2009 at 00:52
It's not too hot to get decent bud, but it is too hot really in an ideal situation, and to get the best out of the plants. I went through 3 different size rvks before i found the one that worked best. I think its worth the expense, as everytime i toke on a joint, i can tell the difference in quality. But i've grown great bud in temps of 30C, just be careful about mites, they love hot temps, and will breed like crazy in anything above 26C. Not allways an issue, but if you do get them, high temps are a killer.

As you get to the winter, the temps in your tent should get real good if you get a decent fan now. My fan was hitting about 26C-28C in the heat we had, un the winter, when we were having the real cold, it was sometimes below 24C with lights on. So its real good, and i dont find the extra temps in the summer aslong as kept under 30C are too bad to deal with, unless like i mentioned, you get spidermites.
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  Quote keller Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2009 at 17:52
bang on solidopc I too went through a couple of rvks, till i settled with the 150mm rvk, I dont know why so many peeps recommend a 125 rvk for a 400watt in a space of 100cm/100cm/200cm tent , I always got about 33C with the rvk 125 and I dont live in a hot country.
The rvk 150 is slighty quieter than the 125 too and with a sound proof ducting u only hear a slight rumble of ait movement , I thought the 150 would have been louder but when u see the length and size of the carbon filter that attachs to this fan u understand why.

   
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  Quote patch Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2009 at 18:18
Had spidermites last year not cool! still i cleared it up and nothing now, + room is proppa sealed up,
 nort gettin in there now bud %3crea%3cy

Thanks for the reply's going to go wit the 400 watt balast, getting a mh bulb and a hps, and also when it came to fans i found this usefull earlier, from a grow shop:

What fan do i need?

if would like to calculate  the size of fan you require simply follow these instructions:

  1. Measure the Height, Length and Width (in metres) of the growing environment.
  2. Multiply together (H x L x W) to give the cubic meter volume.
  3. Multiply this figure by 20.
  4. This is the size of fan required to change the air 20 times in an hour.
  5. Buy the fan slightly above the figure calculated if possible to ensure adequate ventilation

Going to go with somthing simular to the 150 rvk, thanks for the in-put peeps %3c3coint

Oh and anyone used a mantis pro reflector?
will it give alot more light back than a cheap one ?

Patch
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  Quote sarah louise Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2009 at 05:32
The fan calculation is fine for a straight flow of air, if you have bends in your exhaust hose (and you undoubtedly will) you will drop the flow considerably. I'll see if I can find some details on that...

Another alternative would be to leave the existing room ventilation as is and air cool the light separately.

I'd be looking at one of these rather than the mantis pro...



Ablite, air cooled reflector.
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  Quote sarah louise Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2009 at 06:53
Originally posted by sarah louise

The fan calculation is fine for a straight flow of air, if you have bends in your exhaust hose (and you undoubtedly will) you will drop the flow considerably. I'll see if I can find some details on that...


found where I was reading about ventilation...

Originally posted by Rhizome from his Noob's Guide to Grow Room Set-up

Calculating cubic footage is simple- length x width x height = cubic volume. You want a main exhaust fan which can exchange the air in your room in no more than five minutes. I try to budget for three minutes. Let's comprimise at four minutes. Therefore, a 5x5 room with 8' ceilings would require a fan capable of [ 5(l) x 5(w) x 8(h)] = 200 cf. 200 cf / 4 (minutes)= 50 CFM for your fan. Doesn't sound like much, huh?

Now let's get into efficiency factor multipliers. ( This is where it all goes to hell).



Take your unloaded CFM requirement, and add 10 % for each foot of flexible ductwork that you are exhausting thru.( ie- you need to clear a 4x4x6 room thru 10' of ductwork. That's {96 CF /4 (minutes)}= 24 CFM + {(10'x10%)=100%} 24 CFM+100% (of 24 CFM)= 48 CFM. ( Exhaust loaded CFM)

Now take your (E.L.)CFM and multiply it by 1.5 for each 90 degree bend in your exhaust ductwork, cumulitively. ( Ie- you have a loaded CFM of 48 cfm that makes two 90' bends in it's ten foot length. That would be (48 x 1.5)x1.5- or 108 cfm loaded w/ bend factor.)

OK- CFM requirements are adding up pretty quick, and we haven't even talked about odor control. I personally think that carbon filters are the best method of odor control- but I figure that we'll get a healthy debate about this too. I like to put my carbon filter inside the room, near the ceiling. I like to set up the filter before the fan, so that air is sucked from the space, through the filter, through the fan, and then out of the space. This way, all air being pressurized by the fan has already been de-odorized. You can blow through the filter if you mount it after the fan, but be aware that between the fan and the filter there will be a zone of pressurized, stinky air- any leaks in your ductwork moving air from fan to filter will create potential smell issues. ( See primary principles above.)

Take your EL CFM ( including bend factor) and multiply by 1.3 to allow for intake restriction of the carbon filter. Don't forget to allow for ductwork between filter and fan!

So, if we're running a filter that's 3' away from the fan- our total duct length ( in the above example) is now 13'. Let's adjust our math.

We have a 4x4x6 room. Our total duct length is 13'. We're using a filter. Our math now looks like-

4x4x6 room= 96 CF. Divided by 4 minutes is 24 CFM required.
24 CFM + 130% ( 10%x13')= 55.2 CFM ( I'm gonna round to whole CFM, to try to minimize decimal over-runs)

(55CFMx1.5)x1.5= 124 CFM – to allow for our two 90 degree bends.

124 CFMx1.3 ( to allow for air velocity lost to the filter) = 161 CFM.

So we're looking at a 161 CFM fan.

But wait- we haven't even thought about how our light's going to effect this. We could go off into a discussion of determining system effeciency by measuring intake and exhaust temperatures so that we could calc differential temperatures, but I don't know how to make the little “ delta” symbol on my laptop keyboard, so I'm gonna skip that and assign yet another load factor...

For a 250HPS- multiply by .75
For a 400- multiply by 1
For a 600, multiply by 1.3
For a K, multiply by 1.6.

(Let's be reasonable here- I know that my math falls apart if you're running a K in a 4x4x6 space – but is it reasonable to run a K in that space at all? In your very first room?)

So to put a 600 in that room, we'll take our base adjusted CFM and multiply by 1.3 .
161 CFM x 1.3 (lamp factor)= 209 CFM fan/blower to power the ventilation system.

I'm not going to blow out the math to establish what room intake sizes should be to prevent drag on the system- that get's WAY crazy... Instead, I'm going to propose that we use a rule of thumb stating that “ Intake area should be fan CFM x .5 square inches”

Applying this rule, our 209 CFM fan would require an intake area of about 100 sq. inches- or 10” x10”. This does'nt have to be monolithic- two 50 sq” intakes will work as well as one 100 sq “ intake. You can check your intake sizing by just cracking open the door to the room and firing the fan- if the door moves at all, you need more intake.

When shopping for fans, round up- if you need a 209, and your choices are 180 or 240, grab the 240.


The rest of the thread can be found at cannabisdotcom.
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  Quote patch Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2009 at 23:26
Thanks very much sarah,

Going to get a vented reflector now and leave the rest as is,
there's a couple reflectors like the one you showed witch i think are great, one is smaller than the other, not sure witch ill go for yet but sure there both quite good.

Ill just have to cut some more hole's in my grow room to take the extra hoses ill need and a fan to accompany the reflector...
No biggie, just a jigsaw, gaffa tape and 10 minites of time..

Thanks all and ill get some pic's when i have all the gear and installed :P

PaTcH  %3cot%20smoki%3cg
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  Quote sarah louise Quote  Post ReplyReply Direct Link To This Post Posted: 13 July 2009 at 06:35
Originally posted by patch

there's a couple reflectors like the one you showed witch i think are great, one is smaller than the other, not sure witch ill go for yet but sure there both quite good.


Before deciding on one model or the other, check what size lamps they can handle... it varies from one manufacturer to another.

One last thing, unless you are using fan designed to operate in high temperatures, make sure you set up the fan on the cool, fresh air, intake side of the reflector and push the air through the system.
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  Quote patch Quote  Post ReplyReply Direct Link To This Post Posted: 13 July 2009 at 18:20
Originally posted by sarah louise

Before deciding on one model or the other, check what size lamps they can handle... it varies from one manufacturer to another.

One last thing, unless you are using fan designed to operate in high temperatures, make sure you set up the fan on the cool, fresh air, intake side of the reflector and push the air through the system.


Good point and yeh i will defo make sure they can take a 400w bulb etc,
And i will have the in-line fan out side the grow room blowing air through the lamp and out another place away from the cool inlet %3cmoking

Thanks for the input! %3ctar
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