HPS Lighting Questions

[Piru]

I've set up a very small growbox(100cmhigh x 40cm wide x 40cm deep) and was going to buy a 125w CFL but i have been looking around and i can get a 150w HPS full set up for about the same price, maybe a little cheaper. Will this lamp get too hot and create a fire hazard in such a little space?(the box is made of MDF and is lined with a polystyrine backed reflective foil used for protecting walls from radiators(it says it is safe up to 60Celcius). I will get a small computer fan to cool it and i already have a computer fan extracting the air out my chimney so will this be enough to keep it cool and safe? I will probably get a 100w bulb instead because i am worried about the heat issue but is this still to dangerous/dangerous at all? I wont have many plants, maybe 3-4 lowrider#2(it is shelved on one side so i can fit more plants in) will this be enough light for these small plants?
Thanks for all of your help.

[Piru]

Also, will a 100w bulb work with a 150w ballast? Thanks.

[suspect]

more then likely not, dont be so cheap anything less than a 200watt compact fluorescent is a waste of time by the real thing its not that much $$$$$$$$

[Piru]

Originally Posted by suspect

more then likely not, dont be so cheap anything less than a 200watt compact fluorescent is a waste of time by the real thing its not that much $$$$$$$$

Eh? I'm not talking about CFL's, i'm talking of 150w HPS. I WAS going to get a 125/200w cfl but HPS is same price so i'm opting for HPS if it wont get to hot and burn my house down....

[suspect]

0believe me when i tell you that a 200watt fluoro puts out the same amount of lumens as a 400 watt mh
but hey if you want to go you own way then so be it

[itty53]

To answer one question...no, don't use a ballast for any wattage other than what it's for. You'll either hurt the ballast or blow the light, both are bad situations for you and the Fire-Dept.

To put my own opinion, HPS will provide better light than CFLs or any other florescent light. But I can't back that up with any cold facts so I won't try.

[jcj77d]

personally i think that the 125w cfl & 150w hps will put off about same amount of heat, except the hps heat will be more spread out, while the cfl's heat is more localized, but since you in a small box heat is gonna be your prob anyway u go. i dont think the 150w hps will start a fire, unless the bulb directly touches something that will burn, even then i dont think its hot enough to start fire, could be wrong. as far as a 100w bulb working w/ a 150 ballast, dont know, but prob not. do a bench test, take some regular incandesant bulbs put in you grow box to see how hot it gets in there. try to match the watts u want, ex: 2 60w, or 1 60w & 1 100w, or try shooting higher like 2 100w or 4 60w bulbs, just to see. let these run for an hour & check temp, make sure u ture on fans. another tip, drill tiny holes all on top of grow box, heat rises, gives the heat a place to rise out of besides fan. i would use 2 fans one at top & other on other side @ bottom, the top blows hot air out, bottom sucks cool air in. maybe even 3, 2 at top on each side, 1 @ bottom, 1 blows out, 2 suck in. lastly i think your box needs to be taller, otherwise you'll be burning the leaves of your plants. ex: 100cm = 1.6ft, 1.6ft minus light fixture height (say 6") = 1ft left. even w/ a cfl u need to keep light 2-4" from top of plants, that leaves you 8-10" of plant growth, & an hps will prob need at least 6" from top.