Equipment
Mar 4, 2026
Why Does Salinity Keep Rising in My Reef Tank Every Day?
Quick Answer
Daily salinity creep is usually evaporation. Water leaves, salt stays—so top off with fresh RO/DI water, not saltwater.
If salinity rises every day, evaporation is the most common cause.
Why it happens
Only pure water evaporates. Salt remains in the tank, so salinity climbs unless you replace evaporation with fresh water.
How to fix it
- Top off daily with RO/DI fresh water
- Use an ATO for consistency
- Check refractometer calibration weekly
Beginner tip
An ato system is one of the best early upgrades for stability.
Log salinity trends in the ReefBay app so you can catch drift before it stresses livestock.
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