As we know water evaporates and when this happens the salt is usually left behind in the water. This is the reason why we top up the water in the aquarium. If left for long enough then the salinity in the aquarium could change. Not by much but over time it could be a problem.
In this instance there would be to much salt in the water.
The other end of the scale is where there would not be enough salt in the water. This is normally from what is called ‘salt creep’.
Basically salt creep is where salt builds up in areas where water has been allowed to splash. The water has dried and left the salt behind. Over time the salt deposits build up and it looks like the salt is creeping along the pipework, overflows etc where it has dried.
So is it a great problem?
Not really as long as you keep your eye on the salinity during your maintenance periods. If you notice that the salinity is a little bit low then put a bit extra salt into your next water change that you would normally. This will bring it back up to the required level.
If for one reason or another the salinity has dropped considerably then bring the salinity back up to the desired level slowly and not in one big go.
If left unchecked as with water levels then salt creep can build up into a problem but if you keep on top of your maintenance and measure the salinity then it should not become a problem.
The only thing is that salt creep can look a bit unsightly. If I have a build up I normally remove it and place it into the first chamber of the sump. I never place it directly into the aquarium as it may land on a coral and iritate it. In the sump it has time to dissolve into the water and not effect anything.
Other than that salt is expensive and I don’t know about you but I want it in the aquarium!