There is a place in aqua notes light that you can fill in your own params, and it will graph it out for you.
Here is the link for the free version, you don't need a aquacontroller to use the tank params loging.
http://www.neptunesys.com/aquaNotesDownload.htm
My pH and temp is automatically graphed, but my alk, ca, and mg manual.
this is what yours could look like...
