What is your Specific Gravity

[Boomer]

Not you rgfast, I figrued you were good It is Cheely

 

[BobBursek]

Boomer,
Are you done shoveling snow this morning??????

 

[Boomer]

No, I finished that yesterday, about 3 "

 

[cheely13]

ok Boomer,

I have a RHS-10 ATC refractometer the LFS ordered it for me they said it was the one they use. I calobrated it by the directions using my RO/DI unit. My hydromerter is a big instant ocean one. Now im worried could my salt be way off?

 

[Boomer]

First, you SHOULD not cal a refract with RO/DI water. Hand-Held refracts, such as this one, are set to "salt water" and not seawater. Meaning, water that has table salt in it. The RI (Refractive Index) of seawater is NOT the same as the RI of salt water. On a Lab Grade refract, which these cheap ones are not, they will always read .0015 to low. That means if you are testing seawater, with that refract calibrated with RO/DI, it needs to read 1.028 to equal 1.0265, as 1.0265 + .0015 = 1.028. The issue with these cheapo's is the quality of the optics. We have found them to be off from a NSW std 1.0265 from ~1.023 ( 31 ppt) to 1.0265 (35 ppt). That is allot, as much as ~ 4 ppt or 0.003 off and not +/- .001 or Sg or +/- 1 ppt as Salinity. If you cal them in Pinpoint 53 mS. a mock seawater, you can get them right on the nose @ 1.0265. They will be fairly accurate for a range of about 1.023 - 1.030.

Your 1.024 vs 1.025 that falls within the accuracy range for either of +/- 0.001. When IO hydrometers are not properly cared for they will read low, which is what you may be seeing here. If one lets seawater dry out in it that salt collects on the needle making it heaver. Thus, it reads lower than it should. When ever these swing arms types are used, they should be washed well with RO/DI water, left wet/damp and put in a plastic zip lock bag. And then soaked in a pH 4 Buffer, like those for cal pH probes, ovenight 2-4 times / year.


edit:

I'm having a bad day on the key board and with the head. So, this has been edited about 5 flipp'in times

 

[cheely13]

Thanks Boomer that was very helpful sorry im still pretty new at this about a year in. Now this Pinpoint 53.0 mS i take it its saltwater how do i get some of it I would really like to make sure my testing is accurate. Whats the point of checking if you are doing it wrong and I want to try and make sure my tank is running the best i can make it.

Ok I found the fluid and ordered me some so I can make sure im accurate. Thanks again Boomer for the lesson and the help

 

[rgfast]

just thought for you Deep 6 users my LFS was using one an would try to tell me others that was all you needed till I took my refactor in the store calbated in front of them and tested their tanks water for them 40ppt. I'll have to leave out their comments but their not preeching deep 6 any more

 

[Schwa]

1.026 using Refractometer @78 degrees I have an ATO so it never varies its spot on . I hear since it is not a NSW Refractometer that the SG is actually less as the NSW REF. take MG and calcium levels into account and the salinity ones just tk salt level into account.

 

[Johnly]

I use a hydrometer only after I have calibrated it in fresh water eg 1.000 at 77F. I like my SG at 1.032 only because I am doing a red sea reef (indo pacific species only!), and that is the natural average in the region (actually it is a little higher, but I like evaporation forgiveness)

 

[reefmadness]

Temp=78
1.025 by hydrometer

 

[Garage1217]

I use a calibrated refract and have always kept my tanks at 1.026