Oxygenate inline between your kettle/wort chiller and your fermentor.  If you are already pumping from your kettle to your fermentor this is a fast and easy way to both measure the temperature and add oxygen to your wort.  The oxygen stone is 2 microns with a 3/8" tube.   You can hard pipe this inline or add any 1/2" MPT fitting for your liquid flow.