Salinity check please

[CoralClasher]

I just got a Tropic Marin hydrometer and I mixed up 30 gallons of new water. Heated to 77 degrees floated the meter and adjusted to 1.026. Heated the new water to match my 80 degree tank and now it’s saying 1.0255 is this about what the temperature conversion should be? My Milwaukee is saying 1.025 that I’ve checked with RODI and two standards. I do have reasons for thinking my digital meter is off. I just want to make sure I’m using the new hydrometer correct. First picture is at 77 last picture is same water just heated to 80. Milwaukee didn’t change from 77 to 80. Thanks for any help.

 

[Cory]

Check this out

http://reefkeeping.com/issues/2004-07/rhf/index.php

 

[CoralClasher]

Check this out

http://reefkeeping.com/issues/2004-07/rhf/index.php

Thanks I’ll have to read it again but I see one example given, natural sea water of 35ppt should read 1.023 at 80 degrees. Is this correct?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks I’ll have to read it again but I see one example given, natural sea water of 35ppt should read 1.023 at 80 degrees. Is this correct?

The picture attachment he posted is what you'd use to see that the temp shift with the hydrometer is about what you expect.

 

[YankeeTankee]

As you heat the water you would expect the hydrometer to read a lower salinity so that makes sense, did I say that correctly @Randy Holmes-Farley?

Anyway, based on the hydrometer your salinity is around 36. Have you tested the hydrometer against a standard?

Neither are perfectly accurate but if a standard shows the hydrometer is accurate I would tend to trust that a little more than a digital refractometer. But they are both pretty close here, nothing to be concerned over.

 

[CoralClasher]

The picture attachment he posted is what you'd use to see that the temp shift with the hydrometer is about what you expect.

Ok thanks so I’ve been running my reef with too much salt then. Not way to much but would 1.027 for a long time cause RTN problems?

 

[CoralClasher]

As you heat the water you would expect the hydrometer to read a lower salinity so that makes sense, did I say that correctly @Randy Holmes-Farley?

Anyway, based on the hydrometer your salinity is around 36. Have you tested the hydrometer against a standard?

Neither are perfectly accurate but if a standard shows the hydrometer is accurate I would tend to trust that a little more than a digital refractometer. But they are both pretty close here, nothing to be concerned over.

I haven’t checked the new hydrometer. I’ll keep digging for the rtn cause. I’ll use this water as is and see how things look tomorrow. Thanks

 

[Randy Holmes-Farley Verified Community Expert]

As you heat the water you would expect the hydrometer to read a lower salinity so that makes sense, did I say that correctly @Randy Holmes-Farley?

Anyway, based on the hydrometer your salinity is around 36. Have you tested the hydrometer against a standard?

Neither are perfectly accurate but if a standard shows the hydrometer is accurate I would tend to trust that a little more than a digital refractometer. But they are both pretty close here, nothing to be concerned over.

Yes, warmer water is less dense, so reads a lower sg and the hydrometer sinks deeper into it.

 

[CoralClasher]

Yes, warmer water is less dense, so reads a lower sg and the hydrometer sinks deeper into it.

Got it thanks again

 

[ReefPiracy]

This was explaining density over temperature based on different tables so they are saying you better know what your calibration table was set to or your going to have bad time using the wrong table. Your is set to 77 F or 25C table. The floaty thing is a know weight. At a known temperature the density of seawater is an SG. The density changes with temperature so the floaty thing floats different. More density floats higher less density floats lower as the weighted device wont change. So as temperature rises your density got lower so the floaty thing sank giving you a lower reading. They are saying to do a temperature correction. Add .00019 for every 1F over or sub for every 1F under . So at 77 F @ 1.026 or 80 F @ 1.0255 + (3x0.00019) = 1.02607 so yeah sounds like its working correct unless your splitting hairs over 0.00007 or could just be a user error on exact reading. Talks of looking at water line not at the ridge formed on the shaft. Don't have salt build up, water droplets above water line on device. Don't effect the weight of the device.