Need to top off tank

[REEF91]

I’ve been away for a few days and my auto topper was not working I have about 4 gallons missing from my 125 gallon tank ….. do I top off with fresh water or salt water I know it’s usually fresh water because the salt does not evaporate but this is 4 gallons not sure if I should use 4 gallons of salt water or fresh

 

[FUNGI]

I’ve been away for a few days and my auto topper was not working I have about 4 gallons missing from my 125 gallon tank ….. do I top off with fresh water or salt water I know it’s usually fresh water because the salt does not evaporate but this is 4 gallons not sure if I should use 4 gallons of salt water or fresh

fresh....why would you think salt? Just curious.....

 

[Jason Scalise]

I’ve been away for a few days and my auto topper was not working I have about 4 gallons missing from my 125 gallon tank ….. do I top off with fresh water or salt water I know it’s usually fresh water because the salt does not evaporate but this is 4 gallons not sure if I should use 4 gallons of salt water or fresh

fresh water, for sure.
your tank will be relatively 'salt-concentrated' (saltier) now....so to get it back to 'normal' you need to dilute it with fresh.

adding more salt water will result in higher salinity than before the evaporation.

 

[REEF91]

fresh....why would you think salt? Just curious.....

I’m new to this that’s why I’m posting here just wanted to make sure I’m doing this right

 

[FUNGI]

I’m new to this that’s why I’m posting here just wanted to make sure I’m doing this right

No worries.....just was curious....

Also keep in mind salt loss due to salt creep....check salinity once in awhile AND, unless you are making your own s/water, check salinity on any new SW from LFS, as they all keep them at different levels....my old LFS keeps theirs at .021 and my new keep it at .023

 

[FUNGI]

I have a 125G also....used to lose a lot when I went out for work.....bought a redundant ATO just in case LOL....best $30 I spent

 

[rongy]

Definitely freshwater. If you concern about shocking the system, you can do 1 gal at a time every few hours

 

[FUNGI]

I dont think 4 gallons make up much difference in a 125G

 

[Red_Beard]

Ya, fresh. 4 gallons isnt much in a 125. I have extra nems in a 40b, i sometimes space it and it needs 4gallons to top off too, 4 gallons takes me from 1.025 to 1.027-8 and back.