What is your Specific Gravity

What is Your Specific Gravity & How do you measure?

  • Using a Hydrometer

    Votes: 158 38.3%

  • Using a Refractometer

    Votes: 123 29.8%

  • 1.022

    Votes: 26 6.3%

  • 1.023

    Votes: 48 11.6%

  • 1.024

    Votes: 85 20.6%

  • 1.025

    Votes: 161 39.0%

  • 1.026

    Votes: 78 18.9%

  • 1.027

    Votes: 12 2.9%

  • I MEASURE ONLY BY PPT

    Votes: 5 1.2%
  • Total voters
    413
Icebox

Icebox

Member
Dragon, talking about bring a thread back to life... I must say that I shoot for 1.024-1.026. I usually use a refractometer, but I still have my deep six... I use it to get it close, or to spot check when I do not feel like getting the refract out of the box. I can not break the deep six.

Tank temp --- I shoot for 80 +- 2degrees
 
Tuna

Tuna

Member
Boomer said:
NSW and most coral reefs run at near or at 35 ppt, which = a SG of 1.026. I know of very few reefers that run tanks at 1.021-1.023. People are not running it to high but at or near what the animals live in. Many inverts do not far well at low SG like 1.021-1.023. None of the words oceans run this low, which is 29-31 ppt. This 1.021-1.023, more than likely is not SG at all but Density. And Density is not = to SG. Many books and articles have taken 15 C Density tables and just changed the name to SG, which is very incorrect. They then apply these numbers to a SG hydrometer calibrated to 75 or 77 F and go of them and ASSUME they are at normal SG when in fact they are way off. It has taken years to correct reefers on this error.These numbers, 1.021-1.023, are the NSW Density @ 25C (77F) and NOT SG. The only time when these numbers would fall close to NSW would be if one used a std hydrometer calibrated to 15C (60) and the tank water was at 75-77F.
Click to expand...


oops, ive been at 1.022 forever,never had a problem and my corals are outstanding. Im gonna raise it up slowly to 25;) thanks:thumbup:
 
danfish

danfish

Member
why is most tanks on this pol at 1.025 i though the range was 1.020 to 1.023 and i have it at 1.022, am i too low?
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
Two reasons Dan

1. In the olden days it was common practice to run it lower @ 1.023 for FOT and that has rolled over falsely to reef tanks, which should be a 1.025 82 F-1.026 77F.

2. Many in the olden days had things all wrong on SG. They would take a NSW density and change the name to SG, which is not the same. Finally, they were giving values for seawater at 60F, which is not the same as 77-82 F. That wrong number by coincidence is also 1.023, so it was double jeopardy.

So this false low value has plagued us for 2 decades and is hard to remove as it is everywhere.

Lastly, that 1.022-1.023 = 30-31 ppt and there is no reef with that salinity or even close. The avg reef is 35 ppt or 1.026
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
:bugout: and you reminded me of something Billy I left out :( .

That history lesson is for floating/bulb type hydrometers calibrated to 60 F. 99% of the floaters we use are calibrated to 77F. The SeaTest swing arm is self-calibrating to temp as are refracts with ATC, so these are no real issue. That 1.023 came from the # you would want on a 60 F hydrometer, at normal tank temps like 77-80F. People, unknowing with these 77F hydrometers and SeaTest's, would not know this and use the 1.023 for a reading for their 77 F -80 F tank.

The bad thing was that even after I got Tom Frakes to put salinity values on the SeaTest, i.e., 31ppt, 35pp, 38ppt, people just ignored them and used the SG value of 1.023. We would tell people to use 35 ppt and nope 1.023. I would tell them you know the ocean is at 35 ppt right ? "of course I know that, I'm not stupid". Ok, that 1.023 says what on that AS swing-arm ? " Umm 31 ppt" . Ahh, is that the same as 35 ppt. "no but the book says 1.023 is 35" .Does that swing arm show that " ah no" ......me *^$%$^&*^ **&^%$##. It is +20 years Billy and it still is not fixed yet. And it will probably be 20 years before we get this refract thing fixed also :lol: I'll be dead before that, so you take over :)

Randy is trying hard to fix all this also and I tank he is stating to get frustrated also..that is a first for him :bugout: I tried, Tom Frakes has tried and it is not going away yet. This new refract article will be like Randy's fourth article about salinity. And next year you will see a post to calibrate your refract with RO/DI water it will be just ducky for you and accurate. And for years to follow, just like the hydrometers SG/Salinity issue :confused:
 
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