Dimable ballast

So I have a 400W MH bulb in right now about 18" above my plants. I am in a pretty small grow space (closet) and heat has become an issue or at least I think. Usually between 80-85 and up to 90 at the hottest When the Light is on. My plants are 17 days old with the biggest one being a healthy 6" tall and not due to stretching (i don't think anyway) But my question is... to try and get the heat down can I switch to the 50% or 75% setting without losing too much light? How close can I put the light to the plants at the dimmed settings. Thanks for the help any feedback welcomed

This thread seems like a good place to start:
https://www.rollitup.org/newbie-central/373420-400w-mh-light-distance.html

This graph portrays non-dimmable HPS bulbs at different wattages and distances from your canopy, but I still feel it's relatively pertinent.





How are you cooling the bulb, or are you?

Bumping Spheda said:

How are you cooling the bulb, or are you?

Click to expand...

Right now I have a fan kind of pointed up at the end of the light where the bulb points and out the door (ideally) and have another fan blowing in the opposite direction for circulation on the plants and to cool them. I kind of jumped the gun when it came to the grow :/ But hey that is why I am on here! So at this stage I have started reading up on the inline fans and ducting and all that but still have no idea really about anything and don't want to spend a fortune. So any info, advice, suggestions on that would also be very helpful!

90 degrees is pushing it, imo. So long as you have a nice place to draw in fresh air from and exhaust the heat to I'd make a cool tube top priority. The bad part is inline fans are kind of expensive. What's your budget?

For now, I'd say dim the bulb to the point that temps are no longer an issue (85 if you can) and from there judge how far the light needs to be from your canopy. If your hand is uncomfortable from the heat of the bulb at a given distance then your plants will definitely be uncomfortable at that same distance.

I would ideally not like to spend more than $50 but if it was really necessary i would probably be willing more around $100. I have dimmed the bulb to 75% and this is keeping me right around 82.

^^^ Sounds excellent.

Sorry, I should have asked this last night. Is noise an issue? Could you mount the fan remotely in an attic maybe? Some of these inlines sound like jet engines. If this is your bedroom closet it could be absolutely obnoxious if you're trying to sleep while the lights are on. In this case you might want to consider just keeping the bulb at 75% until you have enough funds for a Panasonic Whisper Ceiling ($140 before shipping, there are other models with varying cfm's in the lineup) or something. Maybe you could put the $50 towards LED's? I built a 50W LED light for right around $50 (I had a power cord and wall wart lying around just gathering dust that I was able to use; maybe an old router, or something?) and it doesn't add much heat to my tent.

I'm guessing PC fans don't move enough air to cool a 400W MH bulb, but maybe I'm wrong? It actually sounds silly to me to even consider PC fans, but I'll cover my bases in case that guy exists. I'd suggest looking around the HID section of the forum for ideas, or maybe even repost this thread over there where you can get people more experienced with HID lighting/cooling.

Edit - Just read good things about these: http://www.hvacquick.com/products/r...Remote-Fans-for-Bath/SP-TD-Series-Inline-Fans

Awesome thanks for the feedback that is where I will head next (HID) Man the endless amounts of info on this site are overwhelming

your temps arent too high. starting to push it but ok conditions. wouldnt worry unless it got up to 95 or higher. keep a fan blowing between the tops of your plants and the bottom of the light helps wonders if you arent already doing so.