I approved it on the condition the dish be removed at the end of the lease and holes in the roof sealed or the tenant's security deposit would be charged. 

we bought a home, unoccupied for a long time 6 -8 months and no heat on. during my inspection i pulled a piece of paneling off the wall and exposed the wallboard behind the paneling and found mold. we were able to pitch a lower price and still closed with the bank. once we owned it . we removed the paneling, sprayed concentrated well clorine on the effected walls using a paint sprayer and left the home for several weeks closed up. then started to air the place out. we then used a primer called jammer ( what they use after a fire ) to seal up the walls and proceded to paint the basement and kept the dehumiftifier on after that. so far 4 years have passed and no signs of reoccourance.

They seal any holes, install one way doors and fix soffit/step flashing and everything.  

That being said, we didn't put a product on it like Thompson's water seal or anything like that. 

I had one floor that was so bad the carpets and padding had to be removed then I had to seal off the subfloor/plywood with BIN Primer then lay out a thick plastic sheeting then install new padding and carpet.If you dont neutralize the source of the odor every time the carpet gets wet or damp from humidity it will smell again.

Is it reasonable to think you don't have to pay rent over a seal?

We then primed all the walls and ceiling with Kilz complete to seal any remaining stains. 

I doubt many people will do that but he said there were a growing # of company's in Colorado specializing in cleaning grow houses.If you're going to allow a tenant to grow I would suggest making sure that they have properly sealed up the room(s) whilst having appropriate ventilation to prevent mildew and that all the electrical is to code. 

In addition we still need to seal the apartment so that the alleged problem doesn't continue ? 

The key is to do the work air sealing and insulating the property beforehand.