How to plumb calcium reactor off sump return

[WarDog]

Try to find a fitting called a 'bushing'. Not sure if HD has them, but most plumbing suppliers should (like Noble, {Lougheed at Blue Mtn}).
Mark has one in his picture just before the valve. They take up far less room than a few reducers in line.
Don't think they make a 1" to 1/4", but you could go 1" to 1/2" and 1/2" to 1/4" fer sure.