You don't need two 1/8" holes. You will move a ton of water through a quarter inch combined hole. The thermostat probably won't ever open. Get another thermostat, drill one 1/16th to 1/8th inch hole. When I originally did mine I drilled two 1/8th inch holes 180 degrees apart. I have since downsized to one 3/32nd inch hole. My temps are nice and stable now with no spikes.