Another convert to refractometers

[IslandCrow]

Well, I finally broke down and bought a refractometer to replace my Deep Six hydrometer, and what do you know. . .my specific gravity was not 1.024 like I thought, but 1.030. That could be very well why my corals and anemone haven't been doing as well as I would like. Anyway, I figure it's been like that for awhile and nothing's died, so I'm bringing it back down very slowly, but I guess the lesson learned here is whether you use a hydrometer or refractometer, make sure it's calibrated. Fortunately, no real harm done in my case (that I know of anyway).

One question, though. I ended up getting one of the Marine Depot refractometers. Does anyone know if I have to use distilled water to calibrate it, or will RO/DI work just as well?

 

[Randy Holmes-Farley]

RO/DI is fine.

I'd also make a salt solution to test it a t least once. This thread and article may help:


http://reefcentral.com/forums/showthread.php?s=&threadid=741826

Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm

 

[Gooli]

wouldn't one save money by using the hydrometer and making sure the reading is 0 for tap water? that would mean it's calibrated.

 

[Randy Holmes-Farley]

That doesn't always work well.

 

[IslandCrow]

I'm not sure it's as simple as using tap or even distilled water in a hydrometer and looking for 0, especially since I know mine doesn't even have a 0 on the scale. With Randy's calibration formula, though, it does sound like you can make even a run of the mill hydrometer pretty accurate.

 

[Randy Holmes-Farley]

Yes, it is much more likely to be accurate to match NSW in terms of specific gravity, than to test a hydrometer in fresh water and assume it is also accurate at much higher sg.