I wouldn't assume that every manufacturer has the same sized and shaped crystals, they don't even all have the same ratios and ingredients, that would be a very rough "roughly". If it's not good enough for cooking/baking (you really shouldn't use volume measures for salt unless you specify the exact kind/ crystal size of salt), then i would think we can do better for reefing too
Extremely frustrated by the salinty measuring tools available. Does anyone REALLY know what their salinity level are?
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Ocean’s Piece
Valuable Member
I know you said you don’t like the glass hydrometers but I believe that is the best choice. If you don’t like worrying about turning off all flow, get a graduated cylinder, fill it with tank water, and the place the hydrometer in that. Glass hydrometers are about as accurate as it gets
GeoSquid
Well-Known Member
When I started my first saltwater tank I was also making beer. I just used the hydrometer for checking specific gravity in beer to check salinity. Been using the the same kind for 20 years now. Super easy.
Thats why I say, just get in the ballpark. No way to be 100% sure your readings are spot on. I test incoming water with my corals just to make sure we're both in the same park. Everytime I order from WWC it reads 1.027 on my Milwaukee.. I maintain 1.026. I'm happy
The way I look at that is if my acropora are growing and very happy I keep salinity steady as close as I can.
When I started my first saltwater tank I was also making beer. I just used the hydrometer for checking specific gravity in beer to check salinity. Been using the the same kind for 20 years now. Super easy.
Anyone buying a hydrometer make sure to buy a marine calibrated one, salinity from one substance to another are not measured on the same scale.
SauceyReef
Valuable Member
Yes for sure! I wish the hobby realized how off the salt instruments were. I was dealing with such big problems in my tankand really would never have thought my calibrated refractometer was entirely off and the cause of the issues. After using 4 different ones all calibrated with the solution and having different results I knew I needed a digital refractometer so I bought the milwaukee. Literally best purchase in my 10 years of this hobby. I dialed in my salt to the 100th, and the next hour my tank really showed.
Than I preceded to test all my refractometers with the Milwaukee next. AGAIN - EVERY CALIBRATED REFRACTOMETER WAS OFF. These refractometers were calibrated with their own calibration solution. Some significantly off... I now ask any LFS or reefer friend if they want their water tested and refractometer proven wrong which I have done a few times... I cant even tell you how bad refractometers are let alone hydrometers. IF you think you are dialing down cuz it is "calibrated" you are wrong and your salt is likely off by some.
Yea it is a shame. Almost all are flawed except the floating hydrometer.
This is because all rely on some sort of calibration fluid. I have half a dozen of 35 ppt bottles and most read different.
I have one of the better refractometers around the Vee Gee scientific. Even though it is one of the best and not cheap it still relies on calibration fluid. When you are measuring such a small amount of water it does not take much to throw it off. Also, temp compensation really still needs to be considered. It also seems to take some time to adjust for those that are supposed to automatically compensate for temperature. Temps make a difference. I try to calibrate the same temps as my tank water. I also try to make sure the refractometer is close to the same temp. My problem is my tanks and supplies are in the basement and in the winter it can get cold. So I see the difference temps make on this equipment.
One thing with these bottled calibration fluids to help make it better for constant readings is you need to shake the bottles to make sure nothing has settled out. You also must use a few drops first just incase some dried in the tip. Calibrate it closer to tanks temps by floating it. You use so little in a refractometer it does not take much to throw results off.
The problem with most of the digital ones is they also rely on calibration fluid. You do not know if anything is wrong till you check it to something else. Some do not test the water temps.
Swing arm hydrometers are flawed and really were not originally designed for reefs or to be extremely accurate. It also does not take much to throw them off. A little bubble or some hard water deposits. I have been in the reef hobby almost 35 years and saltwater fish only longer I used to use them early on.
Honestly, a good floating hydrometer is the only way that really is not as flawed but still is based on how it is made so get one for salinity and a good one.
This is because all rely on some sort of calibration fluid. I have half a dozen of 35 ppt bottles and most read different.
I have one of the better refractometers around the Vee Gee scientific. Even though it is one of the best and not cheap it still relies on calibration fluid. When you are measuring such a small amount of water it does not take much to throw it off. Also, temp compensation really still needs to be considered. It also seems to take some time to adjust for those that are supposed to automatically compensate for temperature. Temps make a difference. I try to calibrate the same temps as my tank water. I also try to make sure the refractometer is close to the same temp. My problem is my tanks and supplies are in the basement and in the winter it can get cold. So I see the difference temps make on this equipment.
One thing with these bottled calibration fluids to help make it better for constant readings is you need to shake the bottles to make sure nothing has settled out. You also must use a few drops first just incase some dried in the tip. Calibrate it closer to tanks temps by floating it. You use so little in a refractometer it does not take much to throw results off.
The problem with most of the digital ones is they also rely on calibration fluid. You do not know if anything is wrong till you check it to something else. Some do not test the water temps.
Swing arm hydrometers are flawed and really were not originally designed for reefs or to be extremely accurate. It also does not take much to throw them off. A little bubble or some hard water deposits. I have been in the reef hobby almost 35 years and saltwater fish only longer I used to use them early on.
Honestly, a good floating hydrometer is the only way that really is not as flawed but still is based on how it is made so get one for salinity and a good one.
So many experts on swing arm hydrometers that never use them.
I also have a Pinpoint conductivity meter. It is easy to calibrate, temperature correcting and reads continuously if you want it to. You can sit it down and let it do it's thing hands free.
I stopped using it after it convinced me my swing arm hydrometer reads perfectly fine though over the course of several months. I still have it though.
I also have a Pinpoint conductivity meter. It is easy to calibrate, temperature correcting and reads continuously if you want it to. You can sit it down and let it do it's thing hands free.
I stopped using it after it convinced me my swing arm hydrometer reads perfectly fine though over the course of several months. I still have it though.
GeoSquid
Well-Known Member
• Specific Gravity hydrometers can be used for almost any liquid. Specific Gravity is a dimensionless unit defined as the ratio of density of the material to the density of water. If the density of the substance of interest and the reference substance (water) are known in the same units (e.g., both in g/cm3 or lb/ft3), then the specific gravity of the substance is equal to its density divided by that of the reference substance (water =1 g/cm3)
SauceyReef
Valuable Member
The Milwaukee has a pretty complex spectral reading system for the salinity and also checks temp. so I like to think as long as the calibration is reading properly (they give you 2 different solutions to double check) everything is spot on.
Grallster
Community Member
I use 3 different methods.
1. Neptune conductivity probe—never right. Only good for watching trends.
2. Refractometer—works ok but needs frequent calibration.
3. Floating hydrometer—the only one I really trust. There are online calculators that deal with temperature compensation (glass hydrometers are made to be used at a target temperature. Mine is 60 degrees. The farther from this target temperature you get—the less accurate it becomes. This makes temperature conversion tables a must).
1. Neptune conductivity probe—never right. Only good for watching trends.
2. Refractometer—works ok but needs frequent calibration.
3. Floating hydrometer—the only one I really trust. There are online calculators that deal with temperature compensation (glass hydrometers are made to be used at a target temperature. Mine is 60 degrees. The farther from this target temperature you get—the less accurate it becomes. This makes temperature conversion tables a must).
I have never used one myself but I heard some people complain about it too.
Fwiw, it doesn't matter so much what temperature the little droplet is you put on there, it matters what temperature the refractometer is. If the glass plate is icecold and you put a warm droplet on, the droplet will cool down fast
Best to have the refractometer close in temperature to the tankwater, or at least the same temperature it was when you calibrated it, dont dunk it in though lol. The atc part is supposed to account for that, but that usually only works for small differences in temperature if at all.
With hydrometers you need to be careful about temperature too though, dont let your sample sit around for 5 minutes in a jug somewhere. And best to use a thin plastic cylinder, if you use a glass one that'll cool down the water to if you don't bring the cylinder and hydrometer to temp as well, but as long as you know the actual temperature of the water in the cylinder, you can calculate the real salinity
Knowing the acctual temperature is the next mess lol
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ca1ore
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Hard to see what the 'fuss' is all about. I've been keeping reef tanks for decades using a typical refractometer. I calibrate it to a 35 ppt solution periodically, and I have no reason to think that it is materially inaccurate. You can keep corals successfully at 34-36; fish at a much larger range. So how important is scientific-caliber accuracy really? Unless you are observably losing salt from the system (salt creep or salt spray) or have a runaway ATO, there's really no reason for salinity fluctuations. If you are worried about water changes, use the same measuring tool for both the tank and the temp adjusted new water.
I did say I try to have it as close to tank temp.
That is also what people do not get about temp compensation it takes little to change the temp. of that little drop of water. Something like a Hanna salinity tester probably does a little better because it actually test the tank temp with a probe.
Dr RBG
Active Member
Consider this:
Are we not seeing the forest for the trees? I think that #1 look at your tank, do you see any changes in the flora or fauna? #2 The most important part is stability
By using multiple non-lab-grade instruments will drive you nuts
. I do not think if you buy a 500 instrument you can be sure it will be correct or stay stable. Your calibration fluid also can change with time. Same for distilled water picking up contaminants
Are you toping off the tank with an automatic system?
The whole idea is to enjoy the hobby and relax.
That's my opinion only others may feel differently.
Are we not seeing the forest for the trees? I think that #1 look at your tank, do you see any changes in the flora or fauna? #2 The most important part is stability
within an acceptable range. By using multiple non-lab-grade instruments will drive you nuts
. I do not think if you buy a 500 instrument you can be sure it will be correct or stay stable. Your calibration fluid also can change with time. Same for distilled water picking up contaminantsAre you toping off the tank with an automatic system?
The whole idea is to enjoy the hobby and relax.
That's my opinion only others may feel differently.
Temp plays a big part, my hydrometer is calibrated to 25c, the scale on the hydrometers are also different, so on a marine hydrometer you would be making sure the reading is 1.0264 whereas on hydrometer made for a different fluid you would not be aiming for the same reading.
Another vote for VeeGee STX-3
Although I am curious that at least one other proponent of VeeGee said to calibrate with reference solution. According to the instructions we are to calibrate against RODI only.
I have two VeeGees and in 5 years I've only had to tweak one of them once.
Although I am curious that at least one other proponent of VeeGee said to calibrate with reference solution. According to the instructions we are to calibrate against RODI only.
I have two VeeGees and in 5 years I've only had to tweak one of them once.
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SauceyReef
Valuable Member
Oh no! I have only heard such good things so far. Crazy how testing salinity is a black hole of equipment and info
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