I've read the reviews and noticed a number of reviews that the LCD jumps around and registers low flow. I faced the same problem. I did some googling and came across a forum post where someone emailed a response from Fluval regarding this issue. The email pointed out that if the guard was in an upright position, it could hold hot water near the sensor. Her recommendation was to mount it at a 45 degree angle. Once I moved mine from vertical to 45 degrees. The LCD has stabilized and is no longer turning RED and the low flow indicator has stopped warning. It's been fine for 3 days. I have the bottom of the heater on the filter inlet of my cooktop. The top of the heater is at an angle to the filter. I bought 300 for my 55 gallons. There was no problem keeping the temperature.
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