Lets talk about salinity!

[Guygettnby]

so today i am talking to a person i met at the fish store who happens to be a diver. we get to talking and some how the whole salinity thing comes up. we discuss back and fourth about what the salinity is in the waters surounding florida. he had told me that the salinity is around .0021 were he was collecting , but that it got higher as he started to surface wich ended up being around .0025-.0026......

now this is not the first time i have heard this and i heard it from different divers as well as 1 LFS. sooo, is this all true and what salinity should we infact be running our tanks at? also is this in fact true? i have only tested the waters around 10 feet deep.

[Luckylouse]

I heard that some reefers are trying to stabilize their Salinity to 0.023... particularly those running Balling light method. Not sure why.

[Randy Holmes-Farley]

I discuss salinity here:

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 1: The Salt Water Itself
http://reefkeeping.com/issues/2007-03/rhf/index.php

from it:

http://reefkeeping.com/issues/2007-03/rhf/index.php#13

What Salinity to Use?
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. Salinity, however, does vary substantially from place to place.

As far as I know, little real evidence suggests that keeping a coral reef aquarium at anything other than natural salinity 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. Substantial misunderstandings also arise among aquarists as to how specific gravity really relates to salinity, especially considering temperature effects.

The salinity on natural reefs has been discussed in previous articles. 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 salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm).

Fortunately, coral reef aquaria seem rather forgiving with respect to salinity. The range of salinities encountered in what most would proclaim as successful reef aquaria is actually quite large. Don’t agonize over small deviations from natural seawater. You will not notice any benefit changing from 36 or 34 ppt to 35 ppt (specific gravity = 1.0256 to 1.0271). Many fine reef aquaria appear to run at salinity levels as low as 31 ppt (specific gravity = 1.023), but bear in mind that the values that aquarists report (as well as your own measurements) are fairly likely to be inaccurate, so pushing the low or high end of the range may not be prudent.

Bear in mind that if aquarists target salinity values different than 35 ppt, the amounts of calcium, magnesium, alkalinity, etc., will all likely deviate from natural levels as well. For example, making artificial seawater to a low salinity will normally result in low values for these parameters and may require adjustments.

[Guygettnby]

thank you for chiming in randy. so do you think it is possible for the salinity to be different at different depths in the same area? just seems kinda wierd to me but then again i dont know too much about this kinda stuff. i just try to act the part :lol:

[bertoni]

In an area with freshwater streams or rivers entering the ocean, there will be differing salinity at different depths. Same for areas with rain or lots of evaporation. :) There are also large-scale water currents (like the Gulf Stream) that will affect salinity.

[Boomer]

Guy

Yes Salinity changes with depth due to pressure. Here is a std Salinity Depth Profile.

http://www.windows.ucar.edu/earth/Water/images/sm_salinity_depth.jpg



Jon

I have always waited for a post like this :)

FW is less dense that seawater, so as it leaves a stream outlet the "lighter " water slides across of the top of the "heavier" seawater almost like a sheet. Believe it or not, the ocean out from the mouth of the Amazon River, for almost 100 miles out to sea and called the Amazon Plume, can be just a few PPT at times :)

[Randy Holmes-Farley]

he had told me that the salinity is around .0021 were he was collecting , but that it got higher as he started to surface wich ended up being around .0025-.0026......

I wonder how he measured that (most methods are tricky to use underwater), and whether it might have been a temperature effect that he didn't properly account for. :)

[Boomer]

Lucky

I heard that some reefers are trying to stabilize their Salinity to 0.023... particularly those running Balling light method. Not sure why.

In the USA we use a calibrated 25C/77F SG hydrometer, where 35 ppt = 1.0264. In many European countries, where the Balling Method comes from they use a Density Hydrometer, 35 ppt = 1.023 @ 25C/77F. D and SG are not the same thing. The only time SG =D is if he SG hydrometer is calibrated to 4 C. Some also use a 15C/59F SG Hyrometer, where at ~80 F = 1.0233 = 35 ppt.

.0021 were he was collecting , but that it got higher as he started to surface wich ended up being around .0025-.0026......

I also wonder how that was measured and how did he do it ? Those numbers say hydrometer or refract. I'll bet if he was collecting samples at different depths and then measuring them at the surface.

[Guygettnby]

im not too sure how he was taking his measurments to be honest with you. i just found it interesting that i heard it from more then one source, at more then one area. so i am pretty sure they didnt hear it from each other.

maybe they were taking water samples at each depth and then measuring when they got to the surface? would this infact change the readings??

anothing thing is this, if the salinity is infact different at different depths were our corals are collected would that actually change the way our corals are growing? would they not grow better and be more healthy at the salinity at wich they were collected from?

[Guygettnby]

he had told me that the salinity is around .0021 were he was collecting , but that it got higher as he started to surface wich ended up being around .0025-.0026......

I wonder how he measured that (most methods are tricky to use underwater), and whether it might have been a temperature effect that he didn't properly account for. :)


i can ask the LFS wich collects there own stuff from the gulf how they are acuratly taking these measurements but as far as the other 2 people im not sure if i will see them again too ask.... who knows it is a small world after all.

[Randy Holmes-Farley]

You probably are getting few "corals" from that collector. There is a long discussion of salinity in Pacific Reefs here:

http://web.archive.org/web/20030218193420/www.animalnetwork.com/fish2/aqfm/1997/nov/features/1/default.asp

[billsreef]

One other thing that could give lower salinity at deeper water inshore is ground water seepage.

[Guygettnby]

You probably are getting few "corals" from that collector. There is a long discussion of salinity in Pacific Reefs here:

http://web.archive.org/web/20030218193420/www.animalnetwork.com/fish2/aqfm/1997/nov/features/1/default.asp

a good read but i did have a problem understanding some of it :lol:

[jbird69]

I was talking to the owner of my LFS who is a master reefer/tankbuilder. His facility and livestock health speaks for itself. I told him I was keeping my tank around .026. He was not keen on this and said his entire coral system is at .022. I am not saying who's right or wrong, but again, his livestock speaks for itself...perhaps a specific sg within the range being discussed isnt as important as stable sg?

[Boomer]

master reefer/tankbuilder.

That me be in the mind of the beholder :) There are many, very, very,famous reef tanks/systems/aquariums around the world and almost all run .024-.027. There will be a book out on them next year. There is not a known coral reef that has a salinity that low i.e., 29 ppt. Many inverts, other than corals, have issue at salinities that low. I'm not keen on his idea at all but will not knock him of it if he is successful. But i have not seen it either. I have been in this hobby like 40 years and do not know of anybody that runs a full blown reef tank that low and is successful.

perhaps a specific sg within the range being discussed isnt as important as stable sg?


The salinity on coral reefs are not stable / say but fluctuate seasonally. However, everybody here, just about, believes in stability and are not trying to let the salinity fluctuate and down. We were just stating what happens and is known in the ocean.

I will add, him keeping a LFS that low, when most are way above that with their reef tanks and them buying his animals at that low salinity will be very stressful to them when they end up in a customers tank.

[jbird69]

He has the healthiest coral/invert systems I have seen anywhere. Heres a link to his store
http://www.reef-tech.net/index.html

I am sure there are guys out there that top him in reefkeeping but he is VERY good.

The time that we talked salinity, he pulled out a refractometer and let me see for myself.

Again, I am not preaching that a low salinity is the right path, but I am saying that I know of an insanely beautiful 3000g system running at .022. and its not by accident.

With that said. I run mine at .025 :)

[Luckylouse]

Lucky

I heard that some reefers are trying to stabilize their Salinity to 0.023... particularly those running Balling light method. Not sure why.

In the USA we use a calibrated 25C/77F SG hydrometer, where 35 ppt = 1.0264. In many European countries, where the Balling Method comes from they use a Density Hydrometer, 35 ppt = 1.023 @ 25C/77F. D and SG are not the same thing. The only time SG =D is if he SG hydrometer is calibrated to 4 C. Some also use a 15C/59F SG Hyrometer, where at ~80 F = 1.0233 = 35 ppt.

.0021 were he was collecting , but that it got higher as he started to surface wich ended up being around .0025-.0026......

I also wonder how that was measured and how did he do it ? Those numbers say hydrometer or refract. I'll bet if he was collecting samples at different depths and then measuring them at the surface.

Thanks Boomer.

[luther1200]

[QUOTE=jbird69;16028644]He has the healthiest coral/invert systems I have seen anywhere. Heres a link to his store
http://www.reef-tech.net/index.html

I am sure there are guys out there that top him in reefkeeping but he is VERY good.

The time that we talked salinity, he pulled out a refractometer and let me see for myself.

[QUOTE]

How does he keep his Ca/Alk/Mg in balance at that low Salinity? If you miz a batch of any common salt up that low all 3 values will also be low. So he must be dosing quite a bit to make up for it, or has a giant Ca reactor. I just don't see the point personaly. But his tanks look nice so I guess what ever he does it works for him.

[Randy Holmes-Farley]

Again, I am not preaching that a low salinity is the right path, but I am saying that I know of an insanely beautiful 3000g system running at .022. and its not by accident.

Ask him why he keeps it lower than the ocean where those organisms came from (i.e., why he thinks that's better). I'm curious to see his rational. The question isn't, IMO, can it work, but what is best. Bearing in mind that many specific gravity measurements are in error (likely including his refractometer), pushing high or low limits seems fraught with risks that you may be higher or lower than you think and out of an optimal range.

[tmz]

Invertebrates can't osmoregulate like fish can. Their internal salinity is governed by the water around them . They are isotonic.While they may have a range of tolerance for variable salinity allowing them to maintain homeostasis, it is not likely a very broad range.

Some invertebrates seem less tolerant of low range sg than others such as anemones and xenia for example. Perhaps some zoanthids from coastal run off areas would fare well in lower sg. In my experience aiming for 1.026 sg +/- 1 works well.I think anything under 1.024 is precariously low for a reeftank.

Since the sg of the ocean water each specific specimen I keep came from and even where it came from is sometimes unknown, I target the accepted standard for water on the reef.

[wayne in norway]

Yet the accepted standard is likely to be someways away from some reef waters - how would you mix Red Sea organisms with organisms from somewhere else which has a more 'normal' salinity? Or organisms from a semi enclosed lagoon or back reef where agains salinity can be higher. There must be some range else everytime there was a typhoon everything would die.
I would still think it playing with fire, and decided nonoptimal to run a low salinity on a reef tank tho', especially taking into account the error on refractometers and other salinity measuring devices. A measured 1.022 could be that +-2 quite easily.