You should not need to add anything. Yes you will need test kits if you want to know where it is at . And if you have corals that are calcium users such as LPS
you will need to know your levels
and if you plan on dosing you will need to test . However
IF your levels show to be low just increase your H20 changes (not frequencey ) and that should raise it up . I just tested mine and it was a bit low 380 I keep mine at 420 after a H20 change it was up and fine no dosing needed .
Most trace elements can be replenished via H20 changes ...I use to do 10% water changes now I have increased them to 15% -20% weekly and this keeps me where I need to be ... dosing is such a dangerous thing in a nano and can go wrong quickly . When I use to dose I did so via a syringe /drip method over a 8 hour period and tested in between and found that I was getting further by increasing my H20 changes from 10 % to 15%-20% weekly .