The new micros are promising for placement directly in the tank, rather than sumps. The Tunze Osmolator is good but meant for sumps. The Tunze Osmolator Nano uses a float switch rather than an optical sensor and is not so rimmed tank friendly.
I put one of these Micros on a rimless tank with 1/2″ glass. Half inch glass strains the limits of the provided magnets, but they manage to hold. I put another on a rimmed tank with 1/2″ glass. The magnets wouldn’t hold through 1/2″ glass plus trim, so I siliconed the sensor and tube holder in place. When siliconed to the glass right underneath the lip of the rim, the sensor maintains the water line behind the trim. Most ATOS require hacking the rim and other gymnastics to put the sensor in the right location to get the water line to fall behind the bezel, but the tidy dimensions of the Smart ATO Micro avoid the need for everything but a dab of silicone.
The sensor illuminates blue when powered on. I’ll probably obscure the LED.