I was checking out the Aquaria Central sister site, MFK. They have a forum called 'Lessons Learned', which made me think of something that I figured would be best posted here in the Marine Newbie Forum.
When I first started this hobby my LFS advised me to buy a hydrometer, and strongly suggested this one:
http://www.forestry-suppliers.com/product_pages/view_Catalog_Page.asp?id=6565
After all, it's the one they used.
They said it was extremely accurate, as long as I rinsed it between each use as well as making sure there are no air bubbles during the readings. So I bought it.
As most fishkeepers do, I made some mistakes in the beginning. Long story short- my fish developed ich (ugh), and at that time I chose to go the hyposalinity route.
This hydrometer wouldn't go as low as I needed my salinity so my LFS recommended I get a refractometer- yes, more expensive but WAY more accurate. My LFS does not sell refractometers so I ordered one online.
After receiving the refractometer, I tried calibrating it but was having a rough time...or so I thought. My 3-month old hydrometer was giving me a reading of 1.008 while my refractometer was reading 1.013. I just chalked it up to a newbie not being able to calibrate a refractometer. Wrong...
Went back to my LFS and bought ANOTHER Coralife hydrometer. Used it at the same time as my "old" hydrometer....the new one matched my refractometer reading and the "old" one was off by .005. To me, this was a big deal.
Lesson learned. Those cheap plastic hydrometers with the swing arm, at least in my experience, do not last long with accurate readings. As a result, I didn't actually decrease my salinity level for an actual hyposalinity treatment. I was off during the entire process without even knowing it. Lost livestock. It was very frustrating.
Now I'm not blaming the hydrometer for me losing fish! However, had it been as accurate as I thought it was at the time...I believe my life would've been easier.
I now ALWAYS use my refractometer, and make sure it's calibrated. Yes, it is more expensive, but well worth it- accurate, easy to use, reliable, lasts a while (I still have the same one).
Lesson learned.
When I first started this hobby my LFS advised me to buy a hydrometer, and strongly suggested this one:
http://www.forestry-suppliers.com/product_pages/view_Catalog_Page.asp?id=6565
After all, it's the one they used.

As most fishkeepers do, I made some mistakes in the beginning. Long story short- my fish developed ich (ugh), and at that time I chose to go the hyposalinity route.
This hydrometer wouldn't go as low as I needed my salinity so my LFS recommended I get a refractometer- yes, more expensive but WAY more accurate. My LFS does not sell refractometers so I ordered one online.
After receiving the refractometer, I tried calibrating it but was having a rough time...or so I thought. My 3-month old hydrometer was giving me a reading of 1.008 while my refractometer was reading 1.013. I just chalked it up to a newbie not being able to calibrate a refractometer. Wrong...
Went back to my LFS and bought ANOTHER Coralife hydrometer. Used it at the same time as my "old" hydrometer....the new one matched my refractometer reading and the "old" one was off by .005. To me, this was a big deal.
Lesson learned. Those cheap plastic hydrometers with the swing arm, at least in my experience, do not last long with accurate readings. As a result, I didn't actually decrease my salinity level for an actual hyposalinity treatment. I was off during the entire process without even knowing it. Lost livestock. It was very frustrating.
Now I'm not blaming the hydrometer for me losing fish! However, had it been as accurate as I thought it was at the time...I believe my life would've been easier.
I now ALWAYS use my refractometer, and make sure it's calibrated. Yes, it is more expensive, but well worth it- accurate, easy to use, reliable, lasts a while (I still have the same one).
Lesson learned.