Little help with my 250 HPS cabinet design?

[SpicySativa]

Hello friends,

This post is kindof long... Cheers to those who actually read it all .

With information from this site, I was able to successfully complete a rubbermaid tub grow. So I have to THANK YOU ALL for this wealth of information.

Now I am planning to build a second, slightly more classy cabinet. As a patient I have an easy supply of clones, so my plan is to start the clones in the rubbermaid, then move them in to the new cabinet for flowering when they are ready (somewhat perpetual style). I may eventually end up with a mother plant in the rubbermaid, but for now I'd like to explore different strains.

The new cabinet will have dimensions 28" x 34" x 65" tall, and will be powered by a 250 watt HPS. This gives about 35 cubic feet of volume. I'm pretty handy, so there will be a lot of DIY going on. I will be building a bake-a-round style cool tube, and a DIY carbon scrubber (bed thickness of 1", length/diameter dependent of some other variables I'm still working on). The DIY carbon filter and inline fan will be suspended from the top of the cab with bungee (or old bike tube). This will take up about the top 10" of the cab. Not a problem, I will be using the SCROG technique. The cool tube will be just below the scrubber and fan. Air will be drawn through the carbon scrubber, through the DIY cool tube, through the inline duct fan, and out the top of the cabinet.

That brings me to my question... Should I go with a 4" or a 6" duct fan? I am not going to skimp on this. My top choices are the Elicent 4" or 6" or possibly the Soler & Palau (but I have heard about issues using a speed control with these). The bake-a-round is about 4" diameter, so I was hoping I'd be able to get away with the 4" Elicent (about 150 CFM) with a speed control. With that fan, I could lose about 30% of my airflow to the static pressure of the scrubber, cool tube and ducting, and STILL extract about 3 room volumes per minute. I have NO idea how close that 30% is to reality, that's the problem...

The other option would be to go with a 6" fan, but with the extra diameter of the ducting, extra size of the fan, and extra length on both ends of the cool tube for 6" x 4" reducers, it would start to get a little cramped in the upper section of the cab. I don't have enough experience to make this call, but it just seems like a 6" fan would be overkill for this little cabinet. And it would cost a little more, but that's the last consideration.

So what do you think, guys? What would you do?

SpicySativa Reviewed by SpicySativa on 08-08-2010. Little help with my 250 HPS cabinet design? Hello friends, This post is kindof long... Cheers to those who actually read it all :). With information from this site, I was able to successfully complete a rubbermaid tub grow. So I have to THANK YOU ALL for this wealth of information. Now I am planning to build a second, slightly more classy cabinet. As a patient I have an easy supply of clones, so my plan is to start the clones in the rubbermaid, then move them in to the new cabinet for flowering when they are ready (somewhat Rating: 5

[khyberkitsune]

I would make the suggestion of going LED since you're doing a scrog. This will eliminate your choice of needing a 4 or 6 inch fan, as you'll only need a 4 inch inline fan to pull air through the scrubber and push it out the box, and a vent hole at the bottom for air intake/negative pressure. This will also give you more headroom since the typical LED panel is about 2-3 inches thick.

[SpicySativa]

I hadn't given LEDs much thought. It looks like they are rather expensive, and there doesn't seem to be all that much information floating around about them.

I guess I'm just more confident with a tried and true method. I have seen many reports of nice yields from 250 watt lights in cabs about the size I have in mind, but very few reports about LEDs. How much LED power would I need for a footprint of about 6 square feet? How is the light penetration?

Basically, if I MIGHT be able to get away with just the 4" fan for the 250 watt HPS anyway, what's the selling point for the LEDs?

[SpicySativa]

I looked around some more, and the results from the LEDs look very CFL-like. It seems like the plants grow out spindly and "airy".

I guess I fail to see the advantage to LEDs over CFLs or HID, but to each his own.

[khyberkitsune]

I'm getting colas as thick as d-cell flashlights and hard as a rock under a 120w panel, check out my official LED journal in my sig, bottom link.

MOST LED panels aren't properly made - that's about 95% of them on the market eliminated right there.

You should hit me up on yahoo or AIM (see the IM icons to the right of each of my posts? use those) and I'll show you even more great grown stuff under LED that isn't fluffy and airy.

Also look for the "LED Grow Show" here by Stra8outtaweed.

[drudown11]

I'm getting colas as thick as d-cell flashlights and hard as a rock under a 120w panel, check out my official LED journal in my sig, bottom link.

MOST LED panels aren't properly made - that's about 95% of them on the market eliminated right there.

You should hit me up on yahoo or AIM (see the IM icons to the right of each of my posts? use those) and I'll show you even more great grown stuff under LED that isn't fluffy and airy.

Also look for the "LED Grow Show" here by Stra8outtaweed.

i agree with khyber. The LED technology is there, you just gotta sort through the china made bullshit to get anything worth while. Take a look at St8outtaweed's and Moody420 grows and see what they can really accomplish.


I own a 250 watt mh/hps and i wish i had the money to get some QUALITY led lights.

[khyberkitsune]

i agree with khyber. The LED technology is there, you just gotta sort through the china made bullshit to get anything worth while. Take a look at St8outtaweed's and Moody420 grows and see what they can really accomplish.


I own a 250 watt mh/hps and i wish i had the money to get some QUALITY led lights.

I hate that they're so expensive. I'm trying to get the prices down, and I'm succeeding, but it's only other people's prices dropping as they try to compete with their poorly-made panels.

[GROWxMOREx420]

I was looking at a bunch of LED lighting systems at a Cannabis Expo I went to last weekend, they were really fuckin' cool to say the least, but super expensive.

It just seems more inexpensive and practical to go with traditional MH/HPS lighting. IDK, that's just my opinion.

[SpicySativa]

I agree. Very cool but new and expensive. I'd still love an answer to my original question if anyone can help.

[drudown11]

You should be good with the 4 inch fan, I use a 4inch fan for my closet and it works great. \



Are you going to be cooling the bulb, what type of reflector are you using?