Can this affect my fish......

[adacaro]

I am going to do a water change, my gravity is 19. If the water which I am going to use for my water change is 25 will it affect my fish.

 

[quarryshark]

How big a tank and how much of a water change?
.019 is pretty low and if you are trying to raise it, your should only raise it by .001 per day, no faster.

 

[Edmonton Eskimo]

changes in salinity won't affect your fish as much as you'd think. Most specimens that are available for aquarists are collected from shallow waters that see drastic changes in salinity. Mine changes all the time. Ph and temp are far more important.

 

[adacaro]

My tank is 72 gal and I do a 20 per cent water change every two weeks

 

[quarryshark]

I should clarify. If you plan on having any inverts, this level would be bad for them. Fish can handle it well, but inverts cannot.
I still would raise it slowly. PH and temp changes are more important, but raising spg too fast can cause osmotic shock. Any change is a SW system should be slow.
20% in a 72 gallon with .025 spg would be just fine.

 

[adacaro]

Thank you so much for your help.