Looks like your are cycled. <Assuming that you are adding an ammonia source & it remains at zero.> Although to be absolutely sure, you should test that nitrites are zero as well.
The pH drift may be a problem. It is fairly normal to see the pH drop during cycling, and with a large water change, you should be able to get that back to the 7.2 before you add fish.
Water at pH of 7.2 has relatively low buffering capacity. <You can test for the KH
, the theoretical KH
is ~2 degrees.> You prob can keep it stable when you have fish & are doing weekly pwc
's. I would be monitoring that closely for the first few weeks. If it start to drift down, you might consider adding some crushed coral/shells/limestone to increase the buffering capacity & prevent a pH crash.