Nano Calcium Reactor ?

[cstires]

I'm going to be downsizing from my 120 to a 45g tech tank. I am wondering if there is a good nano reactor on the market. I currently am using a MTC MiniCal on my 120, but it will be way to big for my nano.

Any help would be appreciated. I don't really want to go back to dosing manually, or with a dosing pump if at all possible.

Thanks!