I have a Flex 15 new setup that I’m trying to cycle (empty) at 85 F. I’ve read that it will cycle in half the time at this temperature range. I had a Fluval M50 set all the way to 86, but it never got higher than 80 (which was weird because it was turning off/on periodically, as if it was maintaining 80, instead of trying to achieve 86. So I figured I needed a more powerful heater. I replaced it with the M100. It did better, but topped out at only 81.5, set at 86 (still doing the on/off thing). So now I have both heaters in there, at opposite corners of the tank (the M100 is in the sump). We’re climbing again, currently at 82.4. I have 2 thermometers that agree with one another.
Are the Fluval thermostats just plain inaccurate?
Thanks.