ATO…. I’ve been using the reefbreeders Prizim now for 2 years. It’s one of the lower cost ato’s available and works fantastic. I will use it again on other builds.
ATO reservoir…. I personally use a 10 gallon Petco tank that cost $20 as my reservoir. I did add a glass top for evaporation also from Petco for maybe another $20.
Lights…. I started out with AI HD Primes. They are awesome lights. They have all the control you want. I have since upgraded to Reefbreeders photon and will use again.
My friend uses Chinese black boxes over his 125 and you know what? For 4 years now he has had excellent success.
apex… still on my wish list. I do feel it is not necessary to start with and as a new reefer, you might gain more of an understanding of your tank without all the controls. Dosing by hand and etc is not too bad and eventually you can work up to a controller. It’s just another tool to help.. but definitely not required.
tests…. I would definitely recommend Hannah so you are not deciphering colors.
I do like Red Sea for the other stuff like mag, cal, and trace.
just my thoughts as everyone has a different budget and funds available.
Here is my homemade control board and ATO tank