I agree with you about averaging wrong readings. Especially since I just re-tested and the conductivity testers are low again, compared to the refractometer. So now the range of readings for the tank water is 1.0236 (Hanna) to 1.0268 (Hydrometer).Did you just average them all? My problem with this is if you take 5 wrong readings the average is still wrong.
I trust the floating glass hydrometer more than the others. Fwiw my salinity was 28ppt with icp. I used marin labs. I asked how they measured it, with a refractometer. Really? I of course didnt believe it was 28ppt when 3 devices said 1.026 ish
Also, I hope ATI's test is more accurate than Marin Labs.