Chlorine bleach and ammonia are contaminants on their own and when mixed together make deadly mustard gas.

Usually with mold if you can find the source and either remove the building materials as much as possible and or treat it with chlorine mixed with water. 

@Jason J.No toilet would leak that much.A really leaky toilet would be noticeable.I have a lot of chlorine in my water and had to switch to heavy duty flappers.

Instruct the tenants not to use chemicals in the toilet tank, especially chlorine tablets, as they damage flappers and other parts inside the toilet tank. 

especially vacuum up the precipitate after having just added concentrated chlorine (hypo) *fumes*

Wells have been taged by State enviromental depts to shut down or do crazy daily testing and alot more expense for chlorinators etc.  

That is the Bromine that we use in the Tub which works much better than Chlorine at the higher temperatures.

Over a 3 month period, the chlorine caused the sink, the faucet, the stove burners, and all the metal utensils to become covered with surface rust. 

You can go to the big blue discount center and in the spa and swimming pool section pick up a container of chlorine crystals.

. - Monitoring calcium hardness once a year- Maintaining your chlorine levels- Checking the pH- Checking the alkalinity- As the surface of the pool begins to age, the plaster will require repairs- Maintaining the filter and or filter/heater, if is the pool heatedAs far as who should maintain the pool, I would advise hiring an experienced company.