i just got my 400watt set up in my closet i have a couple of fans going but it got well above 90 degrees in there. if i put in a 175 watt using the 400 watt ballast will it significantly lower the temperature enough?

NO DONT!!!!! You cant put any thing in that lamp that isnt 400 watt. Is it a 400 watt hps or a 400 watt mh. If its a hps you can only put hps in the light . if its mh you can only put mh bulbs in the light. If it is switchable you can put a convestion bulb in it hps or mh. good luck with the heat. Try taking the balast out of the box to lower the temp just a little .you need a inline fan my friend.

i have a switchable ballast and reflector, but i was reading other posts of people saying it was fine to put in a lower watt bulb in a higher watt ballast, the only thing was that it would burn out more quickly. i know, i can't set up an inline (i'm renting a house) so i have a couple of fans going all the time. i was using CFL'S but i wanted to bump it up a bit. plus the fans are way too expensive and i've already done about $800 not including seeds and the other odds and ends you find you need along the way.

yeah i agree with you though, i shouldn't do it, i guess i'm sending it back. thanks