Salinity low?

[Kapachuka3]

This seems odd.... no evaporation? Open or closed top you should see something I would think?

Nope nothing really

 

[Azedenkae]

Nope nothing really

In that case just slowly do water changes with higher salinity water.

Or add salt directly to the tank I guess, or keep salinity at 1.021 to 1.022. Opt for one of the options, whatever you feel most comfortable with. Everyone has pitched in with what they'd do or suggest, what are the benefits or drawbacks, so now it is just a choice to make.

 

[Pistondog]

Change salinity very slowly, 0.001 per day. Urchins are very easily killed by abrupt salinity changes, ime.

 

[Randy Holmes-Farley Verified Community Expert]

But I don’t really ever top off my tank with freshwater cause it never seems to evaporate.

How long have you had this tank?

If you have no evaporation, then you also likely have poor gas exchange and should look into that.

I cannot see how you could have no evaporation and still have decent gas exchange.

Typical evaporation is 1-3% of the tank volume daily.