What should I get next to ensure my tank is a success?

[Pistondog]

how do you know if a tank would benefit from MB7?

Tank is only 3.5 months old. +1 to mb7 or Dr tims or equivalent quality
Don't use vibrant, that's algae control

 

[LegendaryCG]

I followed some of BRS advice : MB7 or Vibrant both work apaprently.

BRS is a good resource but is not fool proof I would recommend you look at their recent videos where they say they don’t suggest starting from purely dry rock.

 

[CMMorgan]

I use Macrobacter 7 already (dose half dose every 2 weeks). Unfortunately I don't think I can get an ATO as I do not have a sump system or salt water storage. I mix my salt water a day prior to the WC and check the sg and temp before adding it in. Do you think I could add an ATO somehow?

The ATO tops off your fresh water. When water evaporates, the salinity in your tank rises. You need to be topping off fresh water as it is evaporating to maintain steady salinity. Do you have an RO?