What I do, since the chemical contained in the strip (dichlorvos) is quite dangerous, (the strip is never enough to do you any actual harm) is shut off the ventilation and seal up my grow room with the strip inside during a lights off period and then I take it out, put it back in the pouch it came in and tape the top up. Only 2-3 dark periods should be enough, if you seal up your room adequately. The concentration of vapor builds up quite higher than the ammount it is supposed to reach depending on the size of your grow room. I suggest airing it out as quickly as possible after you have resealed the strip away. Sealing the strip back up actually insured you can use it again and again to "bomb" your room if a problem ever arises. The chemicals are so strong, there is no need to leave it constantly there, the strip is actually designed for unoccupated areas which constantly have new insects coming into them, for example an unused trailer or shack. Once the spidermites or whatever are all dead, your room should be free of them for a while so you can save your strip for another potential invasion.