Ideal Salinity

drcole

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What is your ideal salinity. My tank is at 79 degrees F and has a specific gravity of 1.022. I read in ppt that that equates 31.6 ppt salinity. What is the ideal range you guys have success with??
 
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cloak

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1.024-1.026 has always worked well for me.

I'm sure there have been times over the years where the SG was a little higher or lower than this, but nothing bad ever seemed to happen. Maybe a little pouting, but that was about it.
 
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Randy Holmes-Farley

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https://www.reef2reef.com/threads/o...-reef-aquarium-by-randy-holmes-farley.173563/

Salinity

There are a variety of different ways to measure and report salinity, including conductivity probes, refractometers, and hydrometers. They typically report values for specific gravity (which has no units) or salinity (in units of ppt or parts per thousand, roughly corresponding to the number of grams of dry salt in 1 kg of the water), although conductivity (in units of mS/cm, milliSiemens per centimeter) is sometimes used.

Somewhat surprisingly, aquarists do not always use units that naturally follow from their measurement technique (specific gravity for hydrometers, refractive index for refractometers, and conductivity for conductivity probes) but rather use the units interchangeably.

For reference, natural ocean water has an average salinity of about 35 ppt, corresponding to a specific gravity of about 1.0264 and a conductivity of 53 mS/cm. It often ranges from 34-36 ppt over reefs, but can be higher or lower locally for various reasons such as land run off of fresh water, or evaporation from a lagoon.

As far as I know, there is little real evidence that keeping a coral reef aquarium at anything other than natural levels is preferable. It appears to be common practice to keep marine fish, and in many cases reef aquaria, at somewhat lower than natural salinity levels. This practice stems, at least in part, from the belief that fish are less stressed at reduced salinity. I have no idea if that is true or not, but I've not seen evidence that it is true. Substantial misunderstandings have also arisen in the past among aquarists as to how specific gravity really relates to salinity and density, especially considering temperature effects. For example, the density of seawater is less than the specific gravity, and measurements with glass hydrometers may require temperature correction, but newer devices do not need the aquarist to make corrections. Consequently, older salinity or "specific gravity" recommendations may not actually be referring to the same measurements that aquarists make today, even if the recommended numbers have been handed down

My recommendation is to maintain salinity at a natural level. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than 35 ppt may make good sense. Otherwise, I suggest targeting a target salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm).
 

NY_Caveman

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https://www.reef2reef.com/threads/o...-reef-aquarium-by-randy-holmes-farley.173563/

Salinity

There are a variety of different ways to measure and report salinity, including conductivity probes, refractometers, and hydrometers. They typically report values for specific gravity (which has no units) or salinity (in units of ppt or parts per thousand, roughly corresponding to the number of grams of dry salt in 1 kg of the water), although conductivity (in units of mS/cm, milliSiemens per centimeter) is sometimes used.

Somewhat surprisingly, aquarists do not always use units that naturally follow from their measurement technique (specific gravity for hydrometers, refractive index for refractometers, and conductivity for conductivity probes) but rather use the units interchangeably.

For reference, natural ocean water has an average salinity of about 35 ppt, corresponding to a specific gravity of about 1.0264 and a conductivity of 53 mS/cm. It often ranges from 34-36 ppt over reefs, but can be higher or lower locally for various reasons such as land run off of fresh water, or evaporation from a lagoon.

As far as I know, there is little real evidence that keeping a coral reef aquarium at anything other than natural levels is preferable. It appears to be common practice to keep marine fish, and in many cases reef aquaria, at somewhat lower than natural salinity levels. This practice stems, at least in part, from the belief that fish are less stressed at reduced salinity. I have no idea if that is true or not, but I've not seen evidence that it is true. Substantial misunderstandings have also arisen in the past among aquarists as to how specific gravity really relates to salinity and density, especially considering temperature effects. For example, the density of seawater is less than the specific gravity, and measurements with glass hydrometers may require temperature correction, but newer devices do not need the aquarist to make corrections. Consequently, older salinity or "specific gravity" recommendations may not actually be referring to the same measurements that aquarists make today, even if the recommended numbers have been handed down

My recommendation is to maintain salinity at a natural level. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than 35 ppt may make good sense. Otherwise, I suggest targeting a target salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm).

LOL. I just re-read this last night and was about to post it. Picked up a Pinpoint Salinity Monitor and was making a new calibration solution. I had previously made the one for my refractometer. Works like a charm!
 
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drcole

drcole

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The goal is to become a mixed reef, I have some changes coming when I move in October but would like to get some of the kinks worked out. Would it be appropriate to top off with saltwater in order to raise the salinity??
 

NY_Caveman

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I have used hydrometers, refractometers and now have the salinity probe which measures conductivity. This probe is by far the best.

Hydrometers are iffy and cannot be calibrated (except for doing the math to make adjustments). I find they degrade over time and must be kept clean.

The refractometer has worked well for me, but I find it must be calibrated every time I take it out. I also have always had difficulty seeing through eyepieces (microscopes, binoculars, etc.).

Using conductivity, which is new to me, is very easy and it holds its calibration well. I can leave the probe in the saltwater and add top off water and watch to reach an exact number without constant retesting.

Randy’s article above is excellent for learning the differences and making calibration solutions.
 
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drcole

drcole

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I have used hydrometers, refractometers and now have the salinity probe which measures conductivity. This probe is by far the best.

Hydrometers are iffy and cannot be calibrated (except for doing the math to make adjustments). I find they degrade over time and must be kept clean.

The refractometer has worked well for me, but I find it must be calibrated every time I take it out. I also have always had difficulty seeing through eyepieces (microscopes, binoculars, etc.).

Using conductivity, which is new to me, is very easy and it holds its calibration well. I can leave the probe in the saltwater and add top off water and watch to reach an exact number without constant retesting.

Randy’s article above is excellent for learning the differences and making calibration solutions.

What instrument do you use exactly?
 

NY_Caveman

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I used a hydrometer years ago. For my return to reefing i picked up an AquaMaxx refractometer. I like it but I recalibrate every use. I just picked up a used Pinpoint Salinity Monitor and i am loving it. Whatever you choose, calibrate and test.
 

chipmunkofdoom2

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I used a hydrometer years ago. For my return to reefing i picked up an AquaMaxx refractometer. I like it but I recalibrate every use. I just picked up a used Pinpoint Salinity Monitor and i am loving it. Whatever you choose, calibrate and test.

I can second this. I bought my Pinpoint almost 2 years ago and it has been great. I test the calibration monthly and I just last month had to adjust it. It was only off by 0.2 mS/cm, which is pretty incredible seeing as how I use it almost daily and I haven't had to touch the calibration in almost 2 years.

Conductivity meters are a bit pricey, but after using one I'll never go back to a refractometer, digital or handheld.
 

fnlyreefready

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1.025 for my mixed reef. Are you fish only?
I think mine is at .27 rn we’ll confirmed. And yeah the nems are pouting a little bit you San see they are obviously in decent health still
 

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