400w hps

[manowar]

Hi all,

New grower here and I a question about my setup. It's box I built thats 3' tall by 2' deep and 3 feet long. That's a totally of 6 square feet and 18 cubic feet. I recently purchased a 400w hps that is air-cooled with ducting. It has an attached ballast and I'm running a 465hp squirrel fan thru the ducting to cool the hps bulb.

Now my first question is, will this fan keep my grow box cool enough? If not would some passive intakes (ie2-3 light-blocked holes on the bottom) and a 100 cfm 4" computer fan on the opposite top actively pulling air out covered by a homemade carbon scrubber be enough to do the trick?

If not, what do you experts out there suggest to keep the box cool enough?

Finally, how many full size plants can I scrog under this light? I was thinking 2-3, but I don't want it overcrowded in there.

Thanks for all the help

PS I'll try and post pics of it when its finished and thru the grow

[BlueBear]

I would try the squirrel cage by it self first. I imagine you will suck the air from the box, threw the hood and out of the box? That should work. What are you using for intake?
Adieu

[manowar]

Thanks for the reply Blue Bear!

I just ordered the light and it isn't here yet. I was under the assumption that the air-cooled tube wouldn't be open to the box at all, thus keeping it cool in the box.

The picture looked there was ducting coming from both sides to make a U pattern. There would be an intake hole on one side of the box and an outake hole on the other side (both holes on top of box). One whole would suck fresh air from the outside across the bulb and be pushed out the other hole with the hot air created by the bulb. There wouldn't be any smell this way, as it's all self-contained fresh air not exposed to the plants.

If one end is open to the growbox, then what do I do about smell protection? Can I put a carbon filter over the opening in the grow box or behind the squirell fan?

I was under the assumption that I could just attach a DIY carbon filter to a 100 cfm fan and have another small fan on the tops blowing air toward the carbon scrubber.

The intake would just be passive with 2-3 four inch darken holes on the bottom side opposite the other side where the outake fan are to get circulation from the roots on up.

Sorry for the novel, but what does everyone think about this?

--manowar

[jamstigator]

You *can* do things that way, but there's no reason to, really, unless you're going to do some co2 stuff. If you're primarily growing for yourself, forget co2, and just use one big fan to pull the air into the box via passive intakes, over your light, down some ducting, and then push that (stinky) air through a carbon filter and expel it out of the box. This is the simplest and most cost-effective way to provide adequate ventilation while keeping odors to a minimum.

Here's a pic of my box, which is probably clearer than my typing. The passive intakes (Doran 8"x8" lightproof darkroom louvres) are at the bottom (I needed two of them to provide enough airflow). The air enters there. Inside the cabinet I have some oscillating fans to mix the air up. The air is then sucked into the cooltube and over the light, then blown out the top through a carbon filter (which you can't see, as it's hidden behind books and crap on top of the cabinet).

[manowar]

Thanks for all the great info Jamistigator!

I just have a couple questions for yo if ya don't mind. Should I be placing the carbon filter between the cool-tube and squirell fan or after the squirell fan (closest to exhaust hole)?

Also, since it looks like I'll be following in your footsteps, I was wondering if you'd mind telling be how you attached your carbon scrubber and what you used to do so. I'll be using a DIY carbon scrubber (link below)

http://www.gardenscure.com/420/security/60127-ryoko-builds-diy-activated-carbon-filter.html

Not sure what you used as a carbon filter, but hopefully this can be adapted over to this setup. The only thing that worries me is that one end of the carbon filter is closed off, and I'm assuming I'll need both ends open.

Thanks again for all the amazing help everyone.

[TheGreenFog]

So I found this journal and CD on my front porch one day...and lo and behold, it was a grow log. In that grow log, the person is using the same growtube and a 250 cfm in-line fan to cool the light. It seems pretty weak. It is set up very similar to Jamstigator's cab with one end open. I haven't read to the end of the log yet. Maybe he/she will switch that fan out for a centrifugal one. What do ya think? It seems that he/she is using the same type of fan to suck exhaust out of a 100 cubic ft area. Do you think thats enough? It says in the log that he/she thinks the fan is not very strong, because when he/she put a papertowel up to the "sucking" end of the fan, the motor started whirring like it was really straining. This is what makes me think its not a very strong fan. Should he/she change it? I'll post some of the pictures as soon as I go grab the CD that was left with the journal. Thanks :D

[jamstigator]

Well, you can suck through a carbon filter, or you can blow through one. If you suck through one, it should be something like this order:

outside air -> inside cabinet -> carbon filter -> tube -> fan -> exhaust

You could swap the positions of the tube and the fan here and not really affect anything. On my carbon filter at least, the air doesn't just come in or go out the holes at the ends, but along the entire length of the filter. And therefore, sucking air through it would have basically mandated that it be INSIDE the cabinet, and it's too big to waste that much precious grow space inside the cabinet.

To blow through it, the filter should be outside the cabinet, in my opinion, as again, it blows out (clean) air all along the length of the filter, and clean air outside the cabinet is exactly what you want. In this configuration, it should be something like:

outside air -> inside cabinet -> tube -> fan -> carbon filter

You could shift the tube and the fan around here in their position if you wanted to, and it'd work the same. I used standard 6" ducting and duct connectors to attach the filter (which itself came with a 6" duct flange).

Those inline fans can't handle static pressure (e.g., generate suction or blow against resistance), so they aren't really useful for blowing or sucking through a carbon filter. The blades would just slow to a crawl and eventually fry the motor, and you'd get little air movement or filtering even before it died. Centrifugal fans are the best, then squirrel cage fans, then axial/inline/computer fans. Lighting should always be the first concern, but I think fans should be a close second; you get what you pay for, pretty much.

[manowar]

Alright all, thanks for all the great advice. It's much appreciated. Just found out today that there's an unexpected development. The fan I thought I was getting (465 cfm) turns out to only be 265 cfm.

Here's the link ---> http://www.specialty-lights.com/736010.html

All in all, I spent 50 pounds and got an agrosun 400w hps with a really nice reflector that's air-cooled, with a protective glass pane (not remote ballast :() a brand new hps bulb, a new mh conversion bulb, the fan linked above and all the ducting and screw plates I need to hold it in. I'm quite happy. The guy told me he had grown enough (only 1 grow!!) and wanted someone else to enjoy it. Stoners sure are nice peeps.

Now for the question. Will this new dayton 265 cfm fan be enough to keep the hood cool with passive intake and a carbon scrubber, or should I add an active exhaust (120mm 100 cfm computer fan) and attach the carbon scrubber to that?

Once again, thanks for the help

[BlueBear]

I would get the active intake just for back up. Those Daytons arn't too strong IMO. May work, may not, but it would be a pain to get it all together then find out that you should of aded the active intake. If you don't need to use the active then you just turn it off, and the hole that it is running threw can still be used as a passive intake. This is the way I did my cab. Some days when it gets too hot I use the active, and on cooller days I just turn it off.
Adieu