I haven't got one myself but a lot of members who have said they keep displaying a message saying low flow. They have moved the heater, increased filtration and flow and still they say the same low flow message.
mine does display low flow occasionally but otherwise works fine. i like being able to scan the tank and see the green display and know the temps good. i wouldnt recommend one for a discus setup though, mine doesnt keep any temp above 30oC very well.
That was me....pile of crap mate, 2000LPH right next to the intake keeps saying LF....i thought the flashing led temp would be cool buts a Pain in the backsdie really
After plugging my heater in for 48hours, I have to agree with bigbruiser. I placed my heater by the intake and the out take area. Continuously flashed saying low flow. I also wanted to heat the water up to 27degrees but it would not go over 25degrees. A really big disappointment.