Lookin' great Warren
Only thing I'll nitpick about is your Alk and Ca balance
@ 7.2 Alk your Ca should be 412
@ 420 Ca your Alk should be 8.3
Too much messing around to make it wonderful, but it wouldn't hurt if you brought your alk up to 7.5 or even closer to 8.0-8.3
And keep your ca where it is but no higher. Any higher and it might precipitace if your alk drops
Raise your alk and keep your ca where it is, IMHO
Have you tested for mag yet ? or even bought the kits ?
Just a thought for you to chew on ....