Using a refractometer

[Jerrod]

I am treating a case of ICK using the hypo salinity method. I have taken the specific gravity to around 1.09 and the salinity is around 10ppt. My swing type hydrometer did not record readings this low so I purchased a refractometer which has readings that go as low as zero for specific gravity and salinity. So far the ICK has cleared up but I have a few more weeks of treatment ahead.

The refractometer is supposed to have automatic temperature compensation and the instructions say to place a water sample on prism and then wait 30 seconds to allow the temperature of the water to adjust to the temperature of the refractometer.

Before I used it I followed the instructions to calibrate it using distilled water and my existing room temperature

My question is about the temperature. I think that specific gravity is temperature dependent so I am wondering if I am getting an accurate reading of the SG in my tank by letting the water adjust to the temperature of the refractometer. My tank temperature is 78 degrees, but the room is around 72. Does anyone have any experience with refractometers or have any advice?

One more thing. The Hypo salinity method seems to have worked because the fish with ICK has recovered and the rest of the fish don't seem to care, and I haven't seen any signs for about 2 weeks. I think I need to keep the salinity low for about 6 weeks to make sure everything is pure.

Thanks

Jerrod

 

[BerlinMethod.com]

I would suggest calibrating the refractometer with RO water that is the same temp as the tank water you will be testing.

The way to do that is get a small bottle of RO water and leave it in your sump for a while to acclimate, then calibrate, then test your actual tank water.

HTH

Regards,
Kris

 

[Len]

Just reread your post. Once you have it calibrated the first time around (per the instructions provided), the refractometer will compensate for temperature for all future uses by shifting the dividing lines in reference to your initial calibration.

-----------originally wrote---------------

Depends on whether your refractometer has built in temperature compensation. Units that do (and that's most models should to the reef hobbyist) automatically shift the dividing lines to correct concentration scale for temperature.

[ October 28, 2001: Message edited by: Leonard ]</p>