salinity probes....

[reefer]

just checking to see if i had my top-off dosage calibrated right. so far the litermeterIII is work'n sweet! at the beginning, the tank's salinity ppm measured at 34ppm, last sunday. today, i measured and accidently grabbed my old meter, and the reading was way low at 31ppm:shock: but the new meter i had read at 34ppm :skeezy: sooner or later i'm gonna need something better and more reliable than these plastic meters. any recommendations? hanna probe or refractometer?
8)

[GaryP]

I recently had a similar problem with discrepancies between my Seatest and Deep Six hydrometers. I just borrowed a refractometer and calibrated them. I had been using the Deep Six but actually found the SeaTest to be more accurate. There was only a difference of about .0005 (SG units) between it and the refractometer. The Deep Six was off by .0015.

I'd also make sure that your hydrometers are clean. From the pic it looks like one has a lot of calcium buildup. Soak them both in vinegar and re-test. Then I would take them to a LFS that has a refractometer and check them against it. Buying a refractometer is a great idea but a bit expensive if you can get around it by calibrating your hydrometer and keeping it properly maintained.

Gary

Gary

[Tim Marvin]

I would drop the salinity also to 32ppm.

[matt]

You can try a big glass hydrometer, too. They're much more accurate than the plastc swing arm ones.

[reefer]

hey tim, i like to keep my ppm at 34. nsw is about 35ppm anyhow. i located some image charts that show salinity readings taken from around the planet (what planet? i dunno). kinda neato though.... looking at the chart, you don't reach 32ppm, until you get near the poles! brrrrr!
thanks for the replies!
8)

[Tim Marvin]

When I have tested my sea test hydrometer against a refractometer the hydrometer read 32 and the refracto read 36. Actually the red sea has been measured as high as 40ppm. Salinity can vary greatly. Depending on the location of the corals to land, rain, run-off, rivers and many other variables can drastically change salinity for short periods of time. If they are near a river the salinity can be much lower. If your corals look healthy and happy though than no worries.

Most people keep the tank between 32-36ppm with no ill effects.