when i had the 400 hps it upped the room temps by about 10 degrees, im not really sure about a 150 though, but if you have 2 in and 1 fan out you should be fine, i think you would be better switching them around though so you have 2 out and 1 in, with a circulating fan blowing across the top of plant, also with the temps of 86 i had them sort of temps with my 400 and it didnt slow them down one bit, so if your plant has no signs of heat stress or other problems i wouldnt worry, by the way whats your fans cfm? also if you did get the hps you wouldnt need the grow tubes, its up to you though m8 just bear in mind though if you add more cfls your heat is going to go up more anyway,