Grow room temp spiking at 90!

My grow room, which is lit by a 400w HPS and is a pretty decent space (medium sized walk-in closet), keeps spiking temp super high! Usually with the light on it floats around 83-88 degrees but I checked it earlier and it was at 90.1

I have proper ventilation with ducting and a fan attachment up top flowing at 270cfm and a fan assisted intake down at the bottem. House temp is roughly 72-74.

Any ideas to get it lower? And how will these temps affect my plants overall health?

Yes this will affect your plant, in a bad way. Heat stress has been known to cause hermies, and will slow down growth of your plant.

Co2?

Do they sell personal cooling units, similar to small heater machines or am I stuck with fans?

im pretty sure they do, but if your house temps are 72-74, theres no reason your grow room should be hitting 90's.

Hes right that doesnt add up. Where is your air inlet coming from? Inlet really helps keep that heat down. Unless its bringing in hot air.

Well it was coming from the master bedroom that the closet is attached to, but I just ran 20 feet of ducting outside, getting the 50, 60's temp we have here in Ohio.

Helped marginally, down to 84.2, but still high.

You'll want the ciculation fan blowing up onto your light,This will keep your light/Ballast cool.

I actually just strung it up so it's blowing directly on it, although it doesn't seem to be helping much. Its at 84 now though, so a little more managable.

Is the reflector enclosed ? Tells us more details about setup. How big is the intake, is it passive ? Where does the air vent out ?

Well, got the temp down pretty low, like 76 or so. But then again, I turned my furnace off and let indoor temp drop to 70 I'll take some pain for these plants.

I have a basic reflector, horrible and unenclosed. Intake is 6" coming from cold outside, but hopefully not for long lol I'm freezing and no it's not passive. My exhaust is on the top of the outside wall of the walk-in closet. So it vents directly to my bedroom.

I just put two little walmart fans on the light and it's running a little lower now, but still - way too hot and annoying with a huge duct running through my room!

In to your bedroom.... Free air freshener! Good to here you got your temps down... Im thinking that your vent fans may not be powerful enough for the space. Do you know the cfm's of the fans and the dimensions of your room?

Room dimensions are 3x10 (I know, pretty long and narrow), and the cfm's on the intake are very low I'm sure, as it is created out of a three dollar Walmart fan. Exhaust however is a speciality fan running at like 270cfm

Another problem solved....

Where is your thermometer at? If it's in the direct light of your hps, this is the problem. That would be radiant temp vs air temp. Radiant temp can be much higher for plants.

I say this because I am running a 430 hps, and it doesn't make sense that your temps are that high. I don't even have ventilation, and my closet is smaller that yours. The only difference could be if you kept your closet shut 100% of the time. I keep my door cracked, and my max temp is around 80.

Is your ballast in your grow room????

Yes, the ballast is in the grow room. Yes, my therometer is directly below the lamp.

And yes, I must be a dumbass.

You're not a dumbass man. I made the same mistake which is why I could tell you that may be a reason for the high temps. I'm still screwing a lot up so you're not alone. Smoke up and be happy.

Check out the grow faq on the temps, and it will tell you a lot about it.
https://www.rollitup.org/view.php?pg=faq&cmd=article&id=218

PS, I have my ballast in my closet and although it does get hot, my temps are still very acceptable so I just leave it in there. If temp is still a problem you can move it out, but it probably won't be if your thermometer dropped as much as mine when I moved it out of the light...

Well it's floating now, low 80's. Okay, I guess but I'd like to see lower.

Thanks for all the input guys!