Changing Salt. How do I know when the old is out??

[dvega101]

I've got 116gl tank and I'm changing the salt by doing 30% water changes once a week. At what point can I consider the salt totally changed? How will I know when the chemistry is being affected by the new salt only ?

Thanks,
Dan

 

[nautical_nathaniel]

There's nothing proprietary substance-wise in any salt aside from some fancy additives and stuff that some brands add and some variation in the concentrations of major and minor elements that make it up. I wouldn't worry about any of the old salt brand lingering and the change shouldn't affect your tank negatively unless you get in a hurry and do a massive water change with the new salt.

I've changed salts a couple times now and as long as you take it slowly everything will be A-okay.

 

[dvega101]

There's nothing proprietary substance-wise in any salt aside from some fancy additives and stuff that some brands add and some variation in the concentrations of major and minor elements that make it up. I wouldn't worry about any of the old salt brand lingering and the change shouldn't affect your tank negatively unless you get in a hurry and do a massive water change with the new salt.

I've changed salts a couple times now and as long as you take it slowly everything will be A-okay.

Would you say the rate I am doing it is proper?

 

[Randy Holmes-Farley Verified Community Expert]

Water changes will never remove every bit of the old salt, and that isn't usually a goal anyway.

What chemistry are you worried about?

30% per week is a lot of changes. 30% per month is more typical. I changed ~1% daily.

 

[PatW]

Yeah, Randy is right. Some of the “old” salt will always remain. At 30% water changes, you have 70% remaining after 1 change, 49% remaining after 2 change, about 34 % remains after 3 changes, about 22% after 4 changes and 15% after 5 changes.

The thing is that an old Ca ion is just as good as a new one. Ions don’t wear out. Generally you can measure and replace most macro nutrients by dosing: Ca, ALK, Mg, nitrate and phosphate. It is the micronutrients that water changes can replace that and exporting any accumulating wastes that normal export systems don’t get. Water changes are a brute force approach but they are very effective.