Advanced Topic Salinity and altitude affect on seawater.

Discussion in 'Advanced Topics' started by Nemos Janitor, 4 May 2014.

  1. Nemos Janitor

    Nemos Janitor

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    This thread is to discuss the affects altitude can have on the salt water we make up. We know that temperature is a big factor in measuring SG or Salinity with most measuring devices. But what about Altitude or barometric pressure.
     
  2. AdS Guest




    to hide all adverts.
  3. butcherman

    butcherman Moderator MASA Contributor

    Joined:
    7 Sep 2009
    Posts:
    11,626
    Likes Received:
    280
    Location:
    Kempton Park
    If anything it will be less. But how much less I can't tell and weather our crud instrument can pick up the difference I do not know. But if you look at water boiling at sea level its 100 degrees. In jhb is like 96.8 or sonething.
     
  4. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Altitude does not sufficiently have an affect to salinity that we can measure with our instruments but it does have an effect on the amount of O2 present in the water.
     
  5. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    We also know that SG and g/ml increases with depth as pressure increases. So whilst the salt we mix may be S=35 at the surface. When measured at depth, the density increases and O2 decreases. Or does it?

    Now the questions that arise are what effect does this have on corals and fish? Should deep tanks salinity be made up at a lower salinity? Should the salinity of tanks at altitude also be made up lower to compensate to the lower O2 .
     
    Last edited: 4 May 2014
  6. carlosdeandrade

    carlosdeandrade

    Joined:
    24 Dec 2010
    Posts:
    8,230
    Likes Received:
    228
    Location:
    North Riding, Jozi
    Surely the depth of tanks will make no notable difference, we are probably talking .00001 points salinty?
     
    Last edited: 4 May 2014
  7. Istio

    Istio

    Joined:
    5 Mar 2011
    Posts:
    145
    Likes Received:
    11
    Location:
    Adelaide, SA
    Show us your salinity profiles for tropical waters. Didn't know that there is necessarily a significant increase in salinity as depth increases.
     
    Last edited: 4 May 2014
  8. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Carlos you are correct in two ways.

    1) the Salinity will not change, the SG and g/ml will.
    2) Most aquariums are relatively shallow and the change in SG or g/ml is small.

    However I am looking at it from another angle. Deep water corals come from these conditions. So we might not necessary need to make up water to counter for the depths of our tanks but to the corals we keep.

    We know that the solubility of O2 is dependent on salinity but that the partial pressure (%) is not. This means that no matter what the salinity the % O2 is the same for sea water as it is for fresh water but the DO is different.

    We can use this calculator to find out the O2 at altitude. For those that live in Johannesburg the altitude is 1680m

    That means that at 25C the O2 at sea level is 6.6177 ppm and at 1680m (Johannesburg) 5.3678 ppm

    Maximum O2 Level Calculator
     
    Last edited: 4 May 2014
  9. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain

    you are correct. Salinity does not change SG and g/ml does. I have edited the post.
     
  10. 459b

    459b Moderator MASA Contributor

    Joined:
    12 Mar 2008
    Posts:
    9,748
    Likes Received:
    789
    Location:
    Cape Town
    Is the salinity and temperature of the oceans constant?
    Last time I checked, the oceans are subjected to the same barometric pressure changes that we are. So if it's such a huge issue, surely the fish would be forced to migrate during storms?
     
  11. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    David 100%. The barometric change at a location will not significantly affect the O2 however. The depth under the water will and the altitude the aquarium is at will also.

    For the reefers at sea level this might not be so much of an issue other than the keeping of deep water corals and fish. But is it an issue at altitude?
     
  12. HOT SAUCE

    HOT SAUCE

    Joined:
    12 Nov 2012
    Posts:
    1,366
    Likes Received:
    18
    Location:
    Manzini / Swaziland
    I'm not sure of the facts.. but I think fish will not migrate during a storm unless the change in salinity is really significant. I think fish can tolerate slight salinity changes as they probably swim trough different waters with different salinity levels.. or do ocean currents even have different salinity levels?

    now the other interesting point is how the salinity or g/ml change with depth. if it has been recorded that those value change in our tanks which rarely are deeper than 1m. how does this apply to the water in the oceans at 5000m depth? or does this not concern us since we rarely keep species from such depths
     
  13. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    As previously stated the salinity will not change at depth. The SG and Density will.

    One can use this calculator to determine the Density change at depth.

    UNESCO equation of state

    Our tanks are not deep enough to worry about the affects of depth. What I am getting at is two things.

    1) How do we "know" or "can we" compensate for the conditions where the corals thrive by changing water salinity and dissolved O2?
    2) the affect altitude has on O2 in our tanks and how to compensate.
     
  14. viper357

    viper357 Admin MASA Contributor

    Joined:
    4 May 2007
    Posts:
    27,988
    Likes Received:
    781
    I can remember Anthony Calfo saying something about a skimmers performance being reduced due to the barometric pressure change during a thunderstorm. It might have some relation to altitude as well, maybe. Not sure if that adds anything to the conversation though. :p
     
  15. shan

    shan

    Joined:
    7 Feb 2008
    Posts:
    689
    Likes Received:
    5
    Location:
    centurion
    This is such a simple question but to answer it is so very complicated. The bigger problem is what is the salinity at the different collection points. In any ocean, the salinity changes due to current, fresh water springs, evaporation in rock pools, people peeing in rock pools and so on and so on and so on. Then the salinity on the boat from the reef to shore, then the holding facility, airport facility, local importer facility, local LFS, and then finally my tank. By the time the fish or coral gets to us, who knows what they go through. I believe more important to us is how we acclimatize the animal in our home tanks.

    Deep water animals are also acclimatized on their way up, for pressure and salinity. I believe that we need to be consistent.

    Please note that this does not apply to animals that have very specific needs.
     
  16. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    David just some thoughts on temperature...

    We find some species in different temperature ranges on our coast. Questions I ask are, is it temperature that is important? Take the marleyi for instance. Is it the temperature or is it increased O2 they seek.
     
  17. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Shan, how does one acclimate for altitude? The O2 decreases at altitude.

    Do we lower salinity to allow for higher O2 dilution and what effect does Henry's law have on the acclimation process?

    Salinity does change per location as does temperature.
     
    Last edited: 4 May 2014
  18. dallasg

    dallasg Moderator MASA Contributor

    Joined:
    14 Dec 2008
    Posts:
    16,771
    Likes Received:
    582
    Location:
    Sandton
    so does altitude affect the salinity or SG???
    it affects the DO, but does that affect SG or salinity, thats the question...

    so someone at the coast make 1L of ASW to 1,026 or 33ppm, then post to me, and i will test :p
     
  19. shan

    shan

    Joined:
    7 Feb 2008
    Posts:
    689
    Likes Received:
    5
    Location:
    centurion
    Yes O2 does decrease with altitude but did anybody actually test our tanks in GP with the ocean in Durbs as an example. With skimmers, air pumps, surface agitation, and all the other toys we have in our tanks that play a part in providing O2 directly or indirectly, is there a statistically significant difference.

    Now the one thing about life is adaptation. If they could not adapt, we all would not have tanks. This is not the greatest of arguments as we all want the best for our pets but if that is really true, then we should really leave them in their natural habitat I.e. the ocean and not a glass box.

    Saying that, would we not stock less at altitude if O2 is indeed less?

    I believe I know too little about salinity to mess with it, hence my above arguments. Good topic by the way, I'm learning.
     
  20. dallasg

    dallasg Moderator MASA Contributor

    Joined:
    14 Dec 2008
    Posts:
    16,771
    Likes Received:
    582
    Location:
    Sandton
    What is Affecting Your Dissolved Oxygen Measurements? Part 2 of 4
     
  21. Nemos Janitor

    Nemos Janitor Thread Starter

    Joined:
    7 Feb 2009
    Posts:
    8,384
    Likes Received:
    286
    Location:
    Joe's Mountain
    Dallas your first question. Altitude does not affect salinity. It affects SG. And it does not affect DO. EDIT it does affect DO at altitude.

    Salinity affects DO.

    O2 affects SG and Density

    On the second part of your post. There is a very simple experiment you can do. Place a hydrometer in a solution of any salinity in a plastic container and seal. Squeeze the container( I use a coke bottle) and watch the hydrometer rise and fall. You can get technical and accurately mix water to S=35 and apply the pressure difference between 0 atmospheres and the atmospheric pressure of where you are testing.

    Shan, it is not about the amount of air we process through skimmers or surface agitation. Henry's law covers that.

    O2 as a percentage is approx 21% at 0 altitude (1 atmosphere) at 140000ft it is also approx 21%.
     
    Last edited: 4 May 2014
Recent Posts

Loading...
Similar Threads - Salinity altitude affect Forum Date
How to get salinity up General Discussions and Advice 17 Nov 2016
Salinity Water Parameters and Additives 10 Jul 2016
Salinity Reading @ 0 Water Parameters and Additives 30 Aug 2015
Urgent help needed Salinity at 1.045 and stocked Urgent Help Needed 28 Aug 2015
Table of Salinity at various Temperatures compared to SG. General Discussions and Advice 12 Jun 2015
Urgent help needed Salinity Spiked Urgent Help Needed 4 Jun 2015
help with salinity Beginner Discussions 8 Nov 2014