Adding freshwater right before a water change?

[homersimpsonlikesfish]

How long after adding freshwater (to replace evaporated water) can I proceed with a 20% water change? I don't want to affect salinity if I do a water change without adding freshwater to bring the tank to the normal water level.

 

[N1tew0lf1212]

Give 30 to 45min of circulation and should be good...probably even less but I always give it some extra time just in case...

 

[Mr. Mojo Rising]

I'm not sure I understand the question, but it doesn't matter when you change your water and/or when you top off.

Topping off is to maintain the same salinity.

Water change should be done at the same salinity as in the tank.

So if you top off and the salinity is 1.025, and the new water is 1.025, go ahead and change the water, no need to wait.

you do have a salinity tester right, like a refractometer or something? You can't have a saltwater tank without a salinity tester. Before you change you water, you test the salinity of the tank and the new water, if it all matches, go for it.

 

[Waters]

You can do the water change immediately. You are just adding minimal amounts of freshwater to keep up with evaporation. That added water will circulate into the tank in minutes.

 

[RandyL]

As long as you have a mark that tells you how far to top off, you could always do the saltwater change first. Just note the gap between the water and the mark, extract the old saltwater and add the new saltwater to the same height (below the mark). Then top off with freshwater to the line.