Salinity

[aaronlp]

I have a quick question about keeping salinity at a certain level...usally it is said to have you SG at 1.025-1.026...but what if you keep it at 1.030...or whatever natural seawater is at? Any problems with keeping a tank like this?

 

[cardiffgiant]

The specific gravity of salt water in most natural reefs is 1.0264 or 35ppt. If you go lower than that with a salt mix you may have to supplement Ca, Kh, and Mg. I wouldn't recommend going higher.

Also, bear in mind that having water that is similar to the folks that you trade or buy corals from will make acclimation easier.

 

[DEEP BLUE SIX]

The specific gravity of salt water in most natural reefs is 1.0264 or 35ppt. If you go lower than that with a salt mix you may have to supplement Ca, Kh, and Mg. I wouldn't recommend going higher.

Also, bear in mind that having water that is similar to the folks that you trade or buy corals from will make acclimation easier.

The above says it all. Plain and simple.

I'm not sure what your goal would be in having it any higher? 1.025 is best in a mixed reef (FISH & Corals) IMO. Of course 1.026 certainly works.
I've heard of a few people that bordered in the 1.026 - 1.027 range keeping primarily corals only.

Any higher than that would not be good for most aquarium situations. Most LFS are not above 1.026 and MANY are way under with average ranges in some of their tanks being 1.023-1.025. Some LFS even use the old trick of lower SG for their fish only tanks. Even lower than 1.023.

Average ocean salinity is 35 ppt. This number varies between about 32 and 37ppt. Rainfall, evaporation, river runoff, and ice formation cause the variations. For example, the Black Sea is so diluted by river runoff, its average salinity is only 16 ppt. However, these are wild conditions in various open ocean scenarios and not on reefs.

It's also questionable what animal/fish you would keep that would do well or need different SG than the normal standards for average home/lfs aquaria.
Unless you had an animal that was used to something much different from where it came from and somehow was kept this way.. up to you aquiring it somewhere.. I'd say that would be pretty rare to have in the hobby.

It's also true in the wild that many migrating fish of the open ocean can pass through varied salinity ranges in their travels. Some around the world. But they are accustomed to these changes gradually as they come and the average range is still in the returned area of 35 ppt.

 

[BuffaloReef]

Others have covered the topic well. The only place I know of where coral and fish found in our systems come from with higher salinity is he Red Sea. Still those inhabitants do well at a 1.025 range. Higher salinity would be stressful to inhabitants since it will be less capable of carrying oxygen and more difficult for livestock to osmoregulate themselves.

All that said I used to average two cheap hydrometers at 1.026 before I bought a refractometer. There seem to be more problems at low salinity than high but keeping a constant and natural salinity would be recommended.