One big issue I had with the Instant Ocean hydrometer is that air bubbles get caught under the floating boom...or attached to the top of it. No matter how small the bubbles are, they can really throw off the reading. If you get a decent refractometer, it is much easier to use, and I think you will get a more consistent reading. Also, if you read some experts, Like Anthony Calfo "Book of Coral Propogation" they recommend using refractometers. for what that is worth.
Finally, having said all of that, I used a hydrometer for years with much success. I really just got tired of jerking around with the bubbles, sticking booms, etc. The refractometer...all you do is wipe it clean, drop a little water on it and look through the scope. |