Hello Hexnut,
The idea to have 2 drive space monitors (one for 10% free space and another for 5% free space) would be required if you want to get an email at 10% free space and an SMS text at 5% free space. On the other hand, if you are simply trying to avoid the text pages at 2 AM, simply set the schedule of the text page Action to only trigger during business hours. See http://support.ipmonitor.com/helps/d8fa6b8474f0434baa35c01e85799a0f.aspx
It should be mentionned that our higher-end monitoring solution, Server and Application Monitor, is much more flexible and allows you to set Warn and Critical thresholds within one Monitor.
Hope this helps.
Chris Foley