The temp shown on the internal thermostate and the actual tank temp is almost the same. Cant tell to the exact temp as the thermostate has no decimal placement. I set the desired temp to 26, so the kick in should be 28. In actual fact it kicks in abt 27.6-27-8 from the in tank thermometer. So i conclude its pretty close.
When i set my flow rate to 1200L/H (using eheim 1250, at 1.2m height), the chill time is 8 mins and the interval is 12min. I also dont know why soo fast, as i'm using a 2ft x 1ft x 1ft tank with 48W T5. Currently toggling abt 3/4 open, the chill time is 5-6mins while the interval has extended to abt 20-30mins. Air con off, tank lights on. Some margin of error is expected..