Salinity meters/hydrometers

[BCOrchidGuy]

Anyone else have trouble with salinity meters? I have 3, all read differently, I bought a glass hydrometer and checked it on RO water, it read 1.003 .I used the three different hydrometers on my tank water and got readings of 32ppt or 1.0235, 37ppt or 1.0275, and 36ppt or 1.0265. My glass hydrometer measured the tank water at 1.029 or 39ppt. That's a rather large range of readings and leaves open some potential for trouble. I didn't really want to have to spend the bucks on a refractometer but I am thinking it's the accurate way to go.

Do I have other reasonable options?

Douglas

And before anyone asks yes they were all soaked in RO water for 24 hours