1.022 specific gravity isn't fine, correct?

[Crabs+Shrimps-69]

Nearly a week ago, I tested my salinity with a hydrometer, and it claimed the salinity was 1.022sg. However, my hermit crabs and snails (currently the only livestock) have all been fine and 1.022sg is actually in the range the hydrometer recommends!

I'm using the dymax hydrometer (https://mydymax.com/products/2-in-1-glass-hydrometer) and I turned the flow off before recording my results.

Am I miss reading the specific gravity?
Also for some reason 1.026sg isn't in the recommended range, it stops at 1.025sg.

 

[Crabs+Shrimps-69]

Update:
Did the test again, still shows 1.023sg.

I tested my hydrometer with @Randy Holmes-Farley's DIY fluid.
If I did the test correctly, my hydrometer was off by 0.002:
That would make my actual result 1.025sg.

I will do another test tomorrow/day after/whenever I next get time incase I made a mistake when performing the test.

 

[gbroadbridge]

Fair enough, but having an absolutely reliable way to measure SG helps keep the financial situation good. I killed some stuff with a refractometer calibrated by a commercial solution that was off before spending the smartest $40 of my reefkeeping career.

It's really not necessary to be completely accurate - consistency is what matters.

Any cheap device can be compared against a standard calibration solution to obtain a reading that is perfectly fine for a reef aquarium.

 

[Malum Argenteum]

It's really not necessary to be completely accurate - consistency is what matters.

Any cheap device can be compared against a standard calibration solution to obtain a reading that is perfectly fine for a reef aquarium.

I agree with that, but I was making a somewhat different point. Both acceptable accuracy and consistency are more reliably had from a tool like the TM, given the possibility of user error in the calibration of refractometers. Even if a refractometer is a better daily use tool for its convenience (which it is), something like the TM can function as a sanity check.

 

[Crabs+Shrimps-69]

Update:

Did the fluid test again; the hydrometer showed the specific gravity at 1.025sg instead this time, but for some reason the specific gravity on the tank was displayed as 1.026!

I'm not sure how there was such a big change in 2 days. The temperature was lower by around 0.5⁰C, but that shouldn't make that much of a difference.

 

[Crabs+Shrimps-69]

Update:

Salinity got up to 1.027sg today even with the lid on (now I'm actually thinking about getting an ATO).

If I did @Randy Holmes-Farley's test correct, my actual reading would be 1.028-1.029sg.

Would you recommend I try and lower the salinity before adding new livestock or should I stop chasing numbers and add new livestock anyway?

 

[Randy Holmes-Farley]

Update:

Salinity got up to 1.027sg today even with the lid on (now I'm actually thinking about getting an ATO).

If I did @Randy Holmes-Farley's test correct, my actual reading would be 1.028-1.029sg.

Would you recommend I try and lower the salinity before adding new livestock or should I stop chasing numbers and add new livestock anyway?

If you believe the values are accurate, I'd lower it to 1.026-1.027

 

[Gumbies R Us]

Update:

Salinity got up to 1.027sg today even with the lid on (now I'm actually thinking about getting an ATO).

If I did @Randy Holmes-Farley's test correct, my actual reading would be 1.028-1.029sg.

Would you recommend I try and lower the salinity before adding new livestock or should I stop chasing numbers and add new livestock anyway?

Yes I would lower your salinity to be 1.026-1.027. You are on the right track though!

 

[Crabs+Shrimps-69]

If you believe the values are accurate, I'd lower it to 1.026-1.027

Yes I would lower your salinity to be 1.026-1.027. You are on the right track though!

Thanks for the advice!
I'm going to start adding some RODI water into my tank and closely monitor the salinity.

 

[littlefoxx]

Anywhere from 1.021-1.023 is typically fine for fish and inverts, corals (yes I know corals are inverts but this is how I differentiate them) you would want it higher 1.024-1.026 as Randy said. I typically keep my reef at 1.025. Alk, calc. mag will be effected by sg the lower sg will have less of those elements typically.

Agree here. I run my fowlr between 1.020 and 1.022 usually. My little nano since it will have corals I run 1.024-1.026

 

[Crabs+Shrimps-69]

Update:

Poured some RODI water into the tank and the salinity was back to measuring 1.022sg, however now that I know the hydrometer reads 0.001-0.002sg lower than the actual value, my real value is 1.023-1.024sg.

Afterwards, I poured a little bit of saltwater into the tank, but before I got a chance to test the salinity, the hydrometer slipped out of my hands, fell onto the floor, and the glass shattered!

Now that I think about it, it might be hard to use a hydrometer when all my coral grows out, so I'm thinking I should get a refractometer.

Currently thinking of getting the Red Sea refractometer since that is one of the only ones I can find locally for some reason.
Does anyone have experience with Red Sea's refractometer?

 

[Randy Holmes-Farley]

When you say poured a little bit, I’m concerned. It seems like the changes are big and should only come about from adding a lot.

Can you estimate the system volume and how much fresh and salt water you were adding in the statements above?

To drop sg from1.028 to 1.022 would require you to add a full 27% of the system water volume.

 

[twentyleagues]

I am thinking your measurements are the issue here. It may be a blessing in disguise to be switching to a refractometer. Take some of the possibility of doing something wrong out of the picture. Refractometers are pretty straight forward to use put a couple drops of tank water on the slide and close it look through eye piece keeping the meter level. I have heard hydrometers should be used in a graduated cylinder to get a proper reading whether that is true or not idk but at the very least all flow in tank should be ceased.

 

[Crabs+Shrimps-69]

When you say poured a little bit, I’m concerned. It seems like the changes are big and should only come about from adding a lot.

Can you estimate the system volume and how much fresh and salt water you were adding in the statements above?

To drop sg from1.028 to 1.022 would require you to add a full 27% of the system water volume.

I've estimated the total water volume I previously had was 40 litres of saltwater (plus a couple of extra litres were added after adding RODI), and I added 8-9 litres of RODI.

I'll add less RODI next time.

 

[Randy Holmes-Farley]

ok, yes, raising and lowering salinity takes much less and is easy to calculate.