Landlord wants to end a month to month

[Kevin Forsythe]

I have a duplex upper and lower with 2 tenants that I bought a few months ago.  One tenant that signed a new 12 month lease with previous owner - that expires in a month.  Likes the place and already has signed another 12 month lease with a 5% increase in rent with me.  Is low maintenance and pays on time good tenant.  The other tenant has been on a month to month for a few years with no rent increases.  Has paid on time for the few months that I have owned the house but has some issues.  They are loud to point others have complained and very messy leaving things on the lawn a lot.  They pay less rent than the other and I have letters to them asking for status if they plan to stay past September (winter in WI is not fun to move).  They have not replied and when talking with others around the house it sounds like they are getting to be a problem.  I would like them to move out I have a tenant willing to move in for market value rent.  Since they are on a month to month and the other prospective tenant want to move in September - do I send them a notice to vacate Aug 1st indicating the month to month is over effective on XX date?  I'm under the impression from others that if they want to stay I can not move them out even if I have a new tenant on deck.  Thank you for your time and opinions.