Looking good, I didn’t like using the gyre pumps in this tank. Only way I could mount them was in the corner sideways so I hope you got a small version of what I had.
I don’t think calcium mag and alk are ever out of balance when using calcium reactors, I have never heard of it but I will read the article if I get time. Also dosing solutions are actually made to be used in equal parts so if a calcium reactor is going to do what your talking about then so will dosing a dosing pump if your doing it in equal parts. As far as I know corals all use the big three in the same ratio.
The tanks going to look good with a black background. I always hated seeing through it.