ORM on CI 3.0?

Greetings!
So I'm completely new in PHP, and have been given the development of a web app as the final project of a subject. It is neither too big or too small, it's supposed to be a ticket sales manager for a local airliner (with quite some restrictions).
Me and my group chose Codeigniter 3.0 as our framework. We read the user manual, completed the tutorial, developed a fully functional database, and coded a basic web interface
But then we stumbled upon the problem of persistency
Some of our friends told us they tried to use Gas ORM with CI 3.0 and had horrible results (which doesn't quite surprise me, I just took a look at it's webpage and seems like it's only compatible with 2.x... and haven't been updated since 2013). They just gave in and downgraded to 2.x so they could use datamapper, which seems to be a highly praised and well documented orm
So long story short, is there any reliable and easy to use ORM for CI 3.x any of you would recommend? Or is downgrading a safer bet?
Thanks in advance!