pre-made saltwater
 

so i made some saltwater on monday, and changed my water on tuesday. I had maybe 2 gallons leftover. I want to bring up my salinity so i will top up with saltwater. My question is the saltwater that i made had no heater or powerhead in it for a couple days now, just an air stone. Will the water still be ok? it doesnt smell bad and i put the heater back in it this morning. I check the salinity with a refractometer and it seems ok. Is it still good to use?

Its fine. Just bring it up to temp before testing it.

+1.... even just use it. Unless you are adding huge amounts no need to heat it up. Room temp is ok enough.