I used that doser for a while however my ONLY complaint about it is the bluetooth connection.
Do not attempt to sit across the room and make adjustments, the BT connection will cause all sorts of unpredictable results. I've emptied entire dosing containers, drained my ATO into my tank, drained my tank overnight (well as much as it would allow) about everything you can imagine has happened with that thing. Left alone it was a GREAT doser however anytime I made a change, it became common practice to double check EVERY setting, even settings I hadn't changed. I once spent about a week updating the firmware because I simply ran out of time restarting the process after each failure, until randomly it accepted the new firmware!
Tech support will advise you to purchase a bluetooth dongle and sit closer to the doser. Not trying to bash your purchase and hopefully they have made some changes, just PLEASE be careful with the settings until you're confident in the way it works. The unit itself and the packaging/accessories are AWESOME.