175 nautical mile range? Not bad for an antenna in the attic! 
To find out what your maximum range is at your location see What is the Maximum Range I can Get? which will tell you if you even need to put your antenna up higher.
Persistence does what the name suggests: makes the airplanes stay on the map even after you’re no longer receiving messages from them (because they’ve flown out of range or landed and shut everything down.)
You can click the gear icon to change your tar1090 settings to un-dim the map and change to a light theme if you want.