Small grow room setup help/heat advice

Is there a cheaper way to add a bit of extra heat into the room to use alongside the 150 bulb I'm using....lol..and not another bulb..!
Like a small heater of sumkind?...but just wondering about drying the room too much?

U need a hygrometer it sound like dude cuz u ain't givin us numbers it no more than $20 tells u max and min temp and humidity. And i would just get a bulb for the 400 ballast cheaper and easier. If heat is a problem u will need an air cooled hood

I think a 400w bulb in that small tent would be way too hot...and then adding a cooltube or sum other type of cooling would start to be expensive.

Anyone know of a cheap way to make sum sort of cool tube...will have a search on here too...

Or is there anyway/device that can restrict the output of a ballast for less wattage