that is if you plant on running LED or Tubes/CLFs in ther .. I would say 6" if you plant on running a big HPS in ther ? (+400W) guess you are if your asking for a cool tube set up . use a littel extra money here on a 6" with speed controle ..
I just build mine: so can I take my large light unit(400w-hps) to pieces?? you have me now thinking about how to enclose my bulb and run some ducting from there to my extractor fan at top of grow. are the clear tubes around your bulbs glass or plastic . I will also "only" run a 4" on that cool hood (my old vent that got to small) with a 600W HPS .. if you run a tube to a open window for fresh/cool air/co2 aso aso aso .. and a link so you can calculat how big vent you need for the room/M3: auldy66. my room and how my 600W HPS lookd before: and sure you can take your HPS appart .. like the heat a HPS make (400 celcius outside the bulb and even hotter inside) the AMP is also pretty high a deathly if you mess with it ..
so if its totaly uncommen for you to work with electricity and you maybe have 10 thumps aswell I wouldnt advice it .. think he said it did lower his temps a few degress celcius .. a hole on top of your refletor with a pice of tube to your vent might work .. Scandinavia so we actualy dont have that high temps .. and with 28C ther can easily get up to 33C in my grow room .. Time for another DIY guide to help you along in your travels. Things are a bit more complicated on this one but the payoff is sweet. This time, I bring you a cool tube and reflector that you can make at home with just a few simple pieces. I looked at a lot of examples and couldn't find a simple solution to having a cool tube and a reflector. So, I decided to just woke some smeed and walk around my local Dome Hepot. After an hour of walking around and fitting things together, I'm pretty happy with the result and so are my plants so I decided to share it with everyone. Here's what you'll need to get started: Pliers Flathead Screwdriver Tin snips (or something similar) Hammer (or something similar :wink: ) 1 x Hurricane Glass Tube from Craft Store -5 inch cylinder 2 x 4-inch duct hangers 2 x longer screws to replace the ones that come with the duct hangers (same width, just longer 'cause you're gonna widen 'em out a bit) 1 x Sheet Galvonized Metal -Find it near the duct work 1 x Tube of Titanium White Paint from Craft Store 4 x 22 gauge (I think that's the correct gauge) metal strips -Find them near the lumber connectors -Get the ones that are thin with just holes going down the middle 1 x package of screws that fit through the holes on the metal strips with nuts 2 x length of chain links 2 x eyelet screws for the chains 2 x hooks for the chains. You'll want to get your reflector measured out and finished first. You'll want to be sure to add a couple of inches as you'll be bending the reflector in a few spots. In order to attach the reflector to the cool tube, you'll need to plan for having a 1-inch middle that will have bends immediately going upward. Look at the pictures and you'll see what I'm talking about. I recommend making a drawing of how you want the folds and then marking it on the metal as I have done here: Please wear gloves when you are cutting this stuff. You can create some really sharp edges and/or shards of metal. Once you cut out the metal reflector from the sheet, you can bend it using the edge of a table, books, vices and wood, however you want. I would not recommend using your hands as clean bends are best for throwing the light.
Now, you're going to take one of your strips of metal and place it in the 1 inch area you have put in the middle. Make the short edge flush with the edge of your reflector and make a dot in the 2nd, 3rd and 7th hole.
Now that you know where your holes are going to be, you can punch some holes in your reflector. I used a screw, a roll of duct tape and a hammer: Now you can go to painting your reflector. You'll probably get 3 coats, maybe 4 out of a single tube. So go ahead, start painting, what are you waiting for? Also, make sure you make your major bends before you paint.