Quote Originally Posted by bigsby
You won't need to push air into the tent. Those things seal up pretty tight so you will achieve negative pressure pretty easily. Plus, you can run into problems pretty quickly both pushing and pulling air. Is oder a concern here? If not, then I would either return one of the fans or run one fan per light.
if you are sucking the air through your light you are going to want to add air into your tent. This serves two purposes. 1. it helps with the pressure in your tent since you are using one fans to suck air out. 2. You will want to be putting fresh air in your tent.

not sure why someone would tell you not to use the 2nd fan. As the above post stated "they are air tight" so, if they are air tight and you are sucking with the one fan to take the heat off the lights, and the tent is air tight you are taken away all the air from your plants.