If you spot just one or two male flowers just nip them off. Also just before your lights come on open your cabinet and check it is completely dark even the tiniest of light leeks can cause plants to hermie. Unfortunately Nirvanas Ice can hermie even with the smallest deviation from the norm. Probably the worst thing you can do though is open the door when it is dark or not keep the light cycle consistant. Don't worry though as removing a couple of plants will give the others more room to grow. You can get a bigger yield with less plants especially if the room is to crowded. Plus you get better air circulation preventing mould later on in flowering.
I'm thinking of designing a grow room/wardrobe with a small part acting as a veg room. A wardrobe that can be see by family and friends and not be recognised as a grow room. I figured I could get 4 to 6 good plants in a space about one metre squared. Then the veg room can be an even smaller space enough for a mother plant and some clones placed higher up on shelves. On the net these cabinets are thousands of dollars but I reckon you could make one for a couple of hundred.
Heres the air cooled hood I use, picked it up cheaper on e-bay. http://www.theonlineelectricalwholesaler.com/catalog/add_to_cart.php?cpath=88_268&pid=310
I found with ICE the stretchy pheno (more sativa) was the biggest yielder and the most potent. It took an extra week to finish but still produced big dense colas. Most of the weight is put on during the final two weeks of flowering.