hps question

My grow tent is custom built in quite a small space. its 60cmx60cmx100cm so it's not very tall. However the area is quite cool and Im wondering if I could get away with putting a 250w hps into the space. I'm currently using cfl but this seems like the next step to get better growth. Obviously the light would be fairly close to the canopy because of limited height though I can LST the plants to keep them fairly short. I know a gap of about 18 inches is often recommended which obviously wouldn't work in this situation. Anyone got any experience with this? Would it work or should I just be getting more CFLS? Currently have an 85w 6400k, a 65w 2700k and a 20w 2700 a couple of inches from the top of my plant.

Thanks!

I would go hps. I got a 60x60x150 secret jardin tent on order and I'm putting a 400w in there....

Yeah If I had 150 I would its just that in 100 cm I'voe got to think that the light will hang about 20cm from top plus about 20cm for a pot leaving 60cm of space in between. How much space do I need to leave between the light and the top is basically what I'm asking I guess.

So I've found a good deal on ebay, should be able to get 400w for about 20 quid (30 dollars) with ballast and reflector. Is this just too much for such a small space? will it burn the plants. For venting I'm running two 12v 80mm pc fans in at the bottom at the front and the same out the top at the back along with a 6 inch clip fan circulating air.

splrs said:

So I've found a good deal on ebay, should be able to get 400w for about 20 quid (30 dollars) with ballast and reflector. Is this just too much for such a small space? will it burn the plants. For venting I'm running two 12v 80mm pc fans in at the bottom at the front and the same out the top at the back along with a 6 inch clip fan circulating air.

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You will need better venting for HID lighting, pc fans belong in pc's not cooling HID lighting. To stand a chance of keeping your grow cool you will need a vented shade and an in-line fan.

alp

Like you said with 100cm height that's tough! I wouldn't squeeze 400w that much. Link to eBay? Sounds cheap for £20. But yeah also even with 250w you will need ton more venting then pc fans and 6" inside. I just ordered 6" clip fan and 5" high velocity fan and filter kit. That should do just about. You would need 4" kit minimum.

Well it's at 15 quid at the minute and what with being collection only I think it will go for cheaper than usual. Could get up to around 30 but I might give it a miss if I'll have to update all the venting. Currently running 170w of cfls in there and I think its even a little chilly for my plant which has drooped slightly (but also grown considerably) since going in there on sunday. Was wondering how to raise the temp slightly and figured perhaps an hps would do the trick. It's in an attic space which isn't fully insulated so gets quite cool.

On the flip side of that, hot plant + cold attic/loft not insulated = heat escaping from roof visible for helicopters. Might be ok with 250w / 400w max but I know I would be paranoid.

That's a great shout actually. I haven't actually really seen how hot those hps lights get as I don't really know anyone who grows but I was watching that bbc doc with martin from eastenders and the coppers in bristol use those heat sig cameras all the time. Think I remember them saying they needed a tip off as well to get a warrant and I keep my hobby very much on the quiet. Can never be too careful though and I hear choppers around my area all the time. Don't know if that's what they're after but it can be a bit worrying. Hmm perhaps i should stick with cfl for now and invest that 30 quid in a couple more 65w bulbs.

They get pretty hott. I usually keep my 150 watt a foot away from da plant with good ventilation and fan on the light and I still reach temps of 84. I like mine to be at 80.