Osmolator 3152 pump acting weird

[Aborin1]

I just bought a 3152 nano for my 20 gal tank. I have a 3155 on my other tank so I’m familiar with tunze products. I just set up the nano and the pump keeps twitching every 10 seconds or so. It’s as if it tries to turn on and stops within half a second. The sensor is installed correctly and in fact, after the initial 20 seconds the pump starts up, the sensor is now maxed out so the pump definitely shouldn’t be trying to activate. This never happens with my other ato. Anyone know why this is happening or what I should do to fix it?

 

[Roy Arena]

Is the cable facing on top of the float switch?

 

[rvitko]

The 3152 has a timer as a safety, the controller will stop the pump anytime it runs a continuous 1 min 45 seconds and the pump will twitch/pulse every 10-20 seconds as an alarm. The only way to reset a time out is to cycle the power. Since the float is not stopping it, my suspicion would be the float is not working due to magnetic interference, the float is a magnetic switch, the black ring in the bobber is a magnet which actuates a switch in the post when it moves. If the float is near other magnets, the controller is near ballasts or other magnetic fields, or the magnet holder is not properly lined up flat on a pane of 3/16-3/8" thick, the magnet holder or other magnetic field may prevent it from working, this is often visible as a bobber that leans like it is repelled or attracted to a magnet. A shim between the outside magnet and glass and eliminating other magnetic fields will solve the interference issues.