Plumbing question and salinity question

[AndyL]

1, Basically easiest way to size returns is to use the calculator on reefcentral, while 1/2" may be enough to get water up to the tank, when it's mixed with air returning (as are most) you generally need bigger. And usually you step up even further expecting future upgrades

2. refractometer I find to be easiest, somewhere around here I have a old fashioned IO hydrometer - but it was rather annoying to use I found.