Salinity

[tangy-tang]

I dont understand fully how salinity works. I have noticed that when my water evaporates the salinity goes up. I would not have thought it would go up. The question that I am most concerned with is how much salt to add when i do a water change to make the salinity to stay the same. All the info on how salinity works would be greatly appreciated.
Thanks,
Mark

 

[alyssia]

Your salinity goes up when your water evaporates because the water evaporates but the salt does not. You need to top off with fresh water as necessary to keep your salinity stable. When you do water changes mix the salt in your water change vessel and make sure it matches the salinity and temp in your main tank. Then aerate and keep it heated for 24-48 hours before putting it in your tank.

 

[lion_crazz]

Yep, water evaporates, not salt. Thus, you now have a hypertonic solution (more salt, less water). Add freshwater to bring level down to where you keep it. What I do is I make a line on my sump with a black marker, that way, I know how much water to put back into the tank to even out the salt level.
When you are making up water for your water change, get a trash can or large bucket solely dedicated to water change water. Make up your water, add salt, add a heater, and a powerhead. Set the heater to the SAME temperature in your tank. Let the powerhead stir the water for a few hours, and at the same time, it is heating the water as well. Check the salinity, and if it is too high, add freshwater. If it is too low, add more salt. Come back in a few hours, test again. Keep adjusting until it is right. Let the powerhead aerate and move the water for 24-48 hours before you do a water change with it.

 

[johnp906]

why the 24-48 hours? does it takr that long to aerate?

 

[jsgreer1]

that will help make sure all the salt dissolves before you put it into your tank.

 

[sleasia]

Just so you know when they say top off with fresh water, if you have R/O water you use that . first adjust to desired alkalinity and ph, you do not need to add salt if you are topping off because you are replacing evaporated water. When you do water changes you use water mixed with salt to match the salinity of your tank (adjusted to ph and alkalinity) because you are replacing water that has been directly siphoned out of the tank and not evaporated...

 

[lion_crazz]

It takes that long to fully dissolve the salt, as well as any chemicals that you put in like alk buffer, etc.
Also, when you dissolve salt, it uses up a lot of oxygen in the water, so you need to replace that and let the oxygen build back up.