You guys are making this measurement way to scientific. The temp error correction factor on the TM Hydrometer is really insignificant in the real world. I agree it is the "Gold Standard" and I have one but would never recommend one for everyday use. They are simply too delicate. I only use mine to verify my Hanna (which always reads low, BTW) so I can apply a correction factor. Years ago, I used a simple Instant Ocean box type and unless you're planning on doing Hyposalinity, I would just go with something inexpensive.