Rent raise during lease

[Zack Whiting]

I bought a twin plex with tenants in place the one tenant was friends with the landlord and she was only charging him 450 for rent and he was supposed to be cutting grass and maintaining outside of the property and that is the reason his rent was low. Needless to say he does not maintain property and I want to raise rent by 300 a month to make the difference for the landscaping. Current lease does say landlord can raise rent in accordance with the "Act" I cannot find anything on this "act". Is there a limit on how much I can raise rent? 
Side note he's mentally handicapped and his care taker owns a shop acrossed the street and uses my property to park cars on when lease states that there is no parking on premises. Would this be something i could evict him for or at least ground to stand on when I raise rent

[JD Martin]

Start over. These things never end well trying to work with the existing tenant who "had a deal". Send them on their way when able and get a new tenant, which will solve all 3 problems (rent amount, grass, and parking).