Is it up to the tenants to maintain it, or do the owners? In summer, you'll need to get it service/cleaned every week or fortnight. That price varies depending on your area, so give a few companies a call. Also, in summer as you use it more often than winter, chemicals will be more.
For us, it costs us around $30 per quarter on electricity (ours is on a cheaper tarif), every 2-3 weeks we'll need to add some chemicals. Could be $20, could be $50, depending on what and how much you need. When it rains, you also need chemicals. We don't get ours serviced or cleaned by anyone, we do it ourselves, but being a rental, it's most likely in the lease agreement that you will have to get it professionally done.
Hope that helps.