[melev]

I don't trust nor use check valves, because invariably the day you need it, it won't work.

The plumbing looks good to me.

I'd rather see 1" plumbing from the Mag 7 all the way to the SCWD, which I would put right behind the tank rather than under it.

Mag pumps do sometimes leak externally. You could probably silicone the coverplate to avoid that, or just use an Eheim instead. With the Eheim, you could go back to 3/4" plumbing again.

I don't think you'll need a ballvalve under the drain line.