salinity

[fishing]

My LFS keeps their saltwater fish in 1.018 SG and recommended the same to me. Me SG is 1.025. Should I gradually lower it to 1.018? Isn't the Ph more stable at 1.025?

 

[aznbob]

I stay at a happy medium of 1.022.

 

[MadManMac]

I have heard that for a fish only tank a lower salinity is ok, but invertabrates and corals will not do well at those levels. If you want to keep anything other than fish, keep it up around 1.023 to 1.025.

 

[Brenden]

Fish stores keep there levels low to keep disease and parasite activity low and stimulate feeding.
If you have anything in your tank other than fish 1.018 will not work. Ph will be harder to maintain as well as all other essential elements. Salt mixes are designed to be mixed at around 1.025 so by lowering the salinity you are also lowering everything else, CA etc. If you have corals and inverts you should maintain levels between 1.024- 1.026 to keep them happy. Be sure you slowly acclimate fish to your salinity. 1.018 to 1.025 is a strressful change for fish if not done over days.

 

[Guest]

Some LFS keep their salinity down to try and keep down outbreaks of ICH. The strange thing is, that they are giving you bad advice about how to keep your tank... The average salinity of natural sea water is around 1.023. This would be the safest range to stay with for a fish only and 1.024-25 for a reef... I hear people say all the time that "what works for you might not work for me". Well, the methods of basic husbandry, really haven't changed in years.
LFS are prone to give very bad advice due to the fact they are in it stricktly for the money and do not take the time to understand how it works. I hope you do not take that advice and stay where you are...

 

[fishing]

is Ph more table at higher sg?

 

[Brenden]

is Ph more table at higher sg?

Yes

 

[Brenden]

The average salinity of natural sea water is around 1.023

Where did you get this info? If this is true why would you increase it for a reef? The idea it to keep them as close to the natural ocean as possible. Natural SW is 35ppt or 1.026. liverocks.com even confirmed this for me when they harvested my LR. I would re-check your source.

 

[fishing]

Thanks for the great advice everyone. You're all awesome!! I'll leave my sg at 1.025. Now I'm a firm believer that LFS's give bad advice just to help profits. Go Figure!

 

[Brenden]

While we are on a role about salinity. Steve-s pointed this out to me and I have read up on it considerably. Salinity and SG are not the same thing. Salinity is how much "salt" is in the water. SG or specific gravity is used to measure density of water. If you would like more information on this I suggest you read this.
http://www.advancedaquarist.com/issues/jan2002/chemistry.htm

 

[zenn]

While we are on a role about salinity. Steve-s pointed this out to me and I have read up on it considerably. Salinity and SG are not the same thing. Salinity is how much "salt" is in the water. SG or specific gravity is used to measure density of water. If you would like more information on this I suggest you read this.
http://www.advancedaquarist.com/issues/jan2002/chemistry.htm

your nsx brenden? Those cars rule IMO.

 

[Brenden]

Yes. I had a green one too but now I am married. I mean...NOW I AM MARRIED I also had a matching yellow TL1000R bike. I decided I wanted kids more than toys that could kill me. I can not blame it on the wife. I guess I just grew up OK back on topic.

 

[zenn]

sorry for the tread hijacking.

 

[Guest]

I did not mention the SG because it would be a long thread and you are right when based on SG.
I also based my comment on readings from 2 different hydrometers, funny as it sounds, from the beaches we swim in.. I took these from here around Jacksonville to Ft. Lauderdale and the average was at or around 1.023. Of course, that number changed slightly I noticed with temperature and area.. Some spots were as high as 1.028 and as low as 1.020...

I am curious about your answer however, that salinity affects PH? I was under the impression that Calcium/Carbonate Hardnes and Alkalinity is where the PH is affected. Maybe redox levels.

I would like to learn how salinity play the part.

 

[Brenden]

The change in your salinity reading if very likely due to the temp of the water as well as FW run off. The surf is not a good place to check levels. SG is directly affected by temp. If you have walked in the surf I am sure you have felt the cold and warm spots. This on top of run off and inlets and pollution and well you know what I mean.
As far as how salinity affects PH..It does not. From my post.

Salt mixes are designed to be mixed at around 1.025 so by lowering the salinity you are also lowering everything else, CA etc.

Since we do not make SW with pure "salt", SG does affect PH. Since a reduced salinity equals a reduced everything else "SG". You can make water with salinity of 1.018 buffer PH as well as 1.025 SW after you dose CA , buffer, etc. What you are really doing by dosing is raising the SG since these additives are denser than water.
Back to the original question.

is Ph more table at higher sg?

Yes higher SG does directly help maintain PH if you are using salt mix.
One thing to remember is a hydrometer actually checks the SG of water but gives you a salinity reading. It is just assuming you mixed oceanic or whatever brand you use and took a reading of the water. It does not know what is making the water denser (higher SG) it is calibrated to the idea you are using salt mix.

 

[Guest]

So really what I get from this, Salinity nor SG has anything to do with maintaining the PH. It is the ingredients added to the salt to closely match the oceans chemistry right? Salt content has nothing to do with PH. That is what I thought.

 

[Brenden]

SG and salinity are not the same thing. SG is basically the weight of the water. Salinity is the amount of salt in the water. If you mix salt water like 99.9% of the people here do...Higher SG will help buffer the PH. A hydrometer does not measure salinity. It measures SG. The SG is converted to a salinity reading for you. The hydrometer manufacturer is just assuming you will be using the hydrometer to measure the salinity in your tank. Since all salt mixes contain the same kinds of salt the hydrometer is just rounded to the average. This, temperature, and no standard for all manufacturers is the main reasons hydrometers are so inaccurate. In your tank mixed with salt mix (presuming you have good salt mix) Higher SG does help buffer your PH due to higher CA levels etc. Salt does not buffer the PH. SG is technically the stuff added to the salt and the salt. Can you mix other things not aquarium related in water and have a high SG and not help buffer PH. YES.. For all practical purposes in our tanks ....Higher SG does help buffer PH.

 

[JG]

So really what I get from this, Salinity nor SG has anything to do with maintaining the PH. It is the ingredients added to the salt to closely match the oceans chemistry right? Salt content has nothing to do with PH. That is what I thought.

"Salt" is a rather generic term. NaCl ( Sodium Chloride or common table salt) is what we most often think of when we use the term, but there are many, many different salts, and a lot of them are found in sea water. Calcium Chloride, Magnesium chloride, Potassium Chloride are a few examples. From a few articles I have read, the Sodium chloride will not affect the pH, but some of the other salts will.

 

[steve-s]

Higher SG does help buffer PH.

Pretty much true. If you look at it from a chemistry standpoint (the make up of the salt content), the higher the salinity value, the higher the chemistry values will be as well. pH stability is affected mainly by alkalinity levels (buffering capacity) and CO2 saturation.

If you take 35 ppt as the "100%" starting point, 23.9 ppt (1.018) will reduce the chemistry by potentially 32%. Your waters ability to keep pH stable will be reduced simpley by reduced alkalinity which is directly related to the salinity of the make up water. You can easily test this yourself by preparing two different batch's of SW. One at 23.9 ppt and one at 35 ppt. You will get significantly different readings for each batch.

Cheers
Steve

 

[Guest]

Thanks guys, I think I am a bit more clear on the subject.

Do have a question tough while on salinity. isn't it true that 35ppt at 72* is 1.025? and the warmer you go the lower the SG? i.e. 80* 35ppt is 1.021 or so? which would mean that you are really looking for 42ppt for a tank that stays at 80 to 82*?