www.saltwateraquarium.com
^This ^
in the hypo salinity thread written by jay hemdal he says you should use a lab grade hydrometer but it’s good to know I can use my regular refractometer.
This is what it say’s: “Before instituting a hyposalinity treatment, you need to decide what measurement units you plan on using – salinity or specific gravity. Then, you must have a very accurate measuring device. A laboratory grade hydrometer is best for accurate specific gravity measurements, or to standardize another measurement means. The device employed must be capable of accurately measuring down to one part per thousand, or one specific gravity unit. Better yet is a device that can read to twice that resolution. For example; capable of measuring 16.5 ppt or 1.0125 specific gravity units. Most handheld refractometers are not accurate enough. Swing arm hydrometers can measure this small of a difference, but they must be first checked for accuracy against a laboratory hydrometer.”
I've never used a swing arm because I've read more negative than positive about them. That said I've also never done hypo.
I think you have more waggle room here than you are thinking and a plain ole refractometer should put you within tolerance either way
@Jay Hemdal is great at what he does and I have a lot of respect for him, but I have to disagree with him on this one. Handheld refractometers are extremely accurate when properly calibrated. In fact, I would venture to say they are more accurate than a hydrometer for our application because hydrometers can be affected by suspended solids whereas refractometers are not.
You’ve seen the article I posted here? I wrote it in response to my coral aquarist who wouldn’t accept that my German laboratory hydrometer had more precision and better accuracy than his refractometer.
www.reef2reef.com
Best is Tropic Marin glass type and I use Hanna Brand digital
Wow, thanks for sharing this. I had not read it! I still think a refractometer is an acceptable tool, as you say yourself: “With practice, most people can achieve an accuracy of .0005 specific gravity units when using a refractometer, and the readings are also very precise.”You’ve seen the article I posted here? I wrote it in response to my coral aquarist who wouldn’t accept that my German laboratory hydrometer had more precision and better accuracy than his refractometer.
He wouldn’t just accept what I was telling him, so I ran a series of bench tests. In the end, he grudgingly accepted my results, but I think he still uses his refract. I wrote the article to pay to cover the numerous lunch hours I spent compiling the data (grin)
Hydrometers are affected by air bubbles, but those are easily seen and removed. Suspended solids at the level seen in aquariums (< 20 PSU turbidity) has no effect.
Here is the article:
Measuring Salinity / Specific Gravity in Aquariums
This article gives an overview of measuring specific gravity / salinity in aquariums.
Randy - please point to a device that you would give a thumbs up to that does not break the bank or infringe on somebody. I suppose I should have at least one. This would be to go along with the TM hydrometer.
I think your expectations of this place are way too high…LOL
