I have both, but I would use the tunze on the AIO/nuvo. It doesn't take up that much room and comes with float switches to prevent over filling. I use the ATK in my sump, connected to my apex. Use a check valve on the tunze to prevent it from back siphoning or draining back in to the reservoir, which creates air bubbles in the pump. Both are great for different reasons.
I also use the ATK in my set up, she’s going to be adding the full apex in the next 12 months hence why I’m favoring the atk which can give here level information..
So it seems both fit and you guys prefer the tunze because of the size?
with the 40 breeder i went with an AI Auga gadget titanium hydrofill ato controller with a toms aqua lifter. on my big (130g tank) went with tunze. ive had the hydrofill and toms over a year and possibly 1 1/2 years, the tunze less about 4 months. they both do exactly what they meant to do. the tunze seems to have a few more alarms and setups ( ex: alarm when the water is too high then the hydrofil). short answer, the tunze! longer answer: if you dont have the money, there is other options. btw, the 40 breeder is my first saltwater tank, so for the hydrofill to work through all the rookie mistakes is quite amazing..
That's all going to depend on ambient temperature, humidity, water temperature, air movement, skimmate pulled, etc etc.
+1 Tunze 3155 osmolator has never failed me, I have experience with 13 different units in the past with maintenance clients tanks and my own systems, multiple built in fail safes, adjustable, precise. Its perfect, plus @rvitko is a super nice guy and provides to notch customer service and product support, Also if you ever decide to sell out or get out of the hobby for a while, plan on getting 60%+ of your money back for it selling it in good used condition, and it will sell quick too! <--- that tells you something!