Question - Replacing Evaporated Water

[RaymondL]

I know that RODI water should be used to top off the tank due to evaporation, does this mean that salinity should always remain constant then - just want to be sure.

For example, assuming a 10 gallon tank that reads 35ppm and evaporates 1 gallon a day, and 1 gallon of RODI water is added each end of day. If 1 day is skipped from adding RODI the salinity should increase yes? Ie. let's say 36ppm. If the next day, 2 gallons(1 gallon missed that day, and 1 gallon for end of existing day) is added instead of 1, it should bring back the salinity to 35ppm - yes?

 

[Gtinnel]

Yes correct.
It’s better to not try to add too much top off water at once though because the salinity swing can be hard on the tank inhabitants.

 

[Gtinnel]

Which is also why an ATO is commonly used. It adds small amounts of fresh water when needed so the salinity stays stable.

 

[Floyd-]

Invest in an auto top off system. Its the one single piece of equipment I would not be without.

 

[SteveMM62Reef]

Second on the ATO. You will still need to check your Salinity. Salt Creep Removal and Skimmer Water will cause your Salinity too drop. You may have to add Saltwater, if water changes are infrequent.

 

[Buckster]

The 3 previous posts are so correct. I have a 180 and I'm so pleased that I have the tunze 3155 ato.

 

[RaymondL]

Second on the ATO. You will still need to check your Salinity. Salt Creep Removal and Skimmer Water will cause your Salinity too drop. You may have to add Saltwater, if water changes are infrequent.

Salt creep - I get much of that outside of the glass along the edges, so that means salt is loss and as a result salinity would drop yes? Versus, evaporation which the salt content remains in the water?

 

[AFHokie]

Salt creep - I get much of that outside of the glass along the edges, so that means salt is loss and as a result salinity would drop yes? Versus, evaporation which the salt content remains in the water?

Correct. However, I've never had salt creep make a measurable drop in salinity. The increase from evaporation is more than enough to negate the drop.