What should I do about the salinity?

[Weboh]

When I did my last water change, I accidentally topped off the tank with RO water instead of saltwater. Now the specific gravity is a bit below 1.020. I know it's supposed to 1.023.

I already have some regular sea salt from the grocery store. Can I add some of that in, or do I need to buy some that's made for fish tanks? Or can I just wait until some water evaporates and put in saltwater then? I don't have anything in there that's too sensitive: clowns, turbo snails, sand sifting starfish, and a Philippine Feather Duster. What do you think the best thing to do is?

 

[SycoCell]

If it were me, I would siphon some of the water out (not sure your tank size) and just mix that water up really quickly and put it back in...

 

[DivingTheWorld]

Only use aquarium salt. You can either mix some up in some R/O and just dump it in. The extra freshwater will evaporate. Or you can let your tank evaporate until it hits the salinity you want, then just add more saltwater. It sounds like you're not using an ATO? It's going to be difficult maintaining a stable salinity without one.

 

[Higher Thinking]

Definitely do not use that table salt. Do you have actually saltwater salt? I would just batch up some and do a water change with higher salinity. Nothing too drastic, but at least get it up a couple hundredths. Then I'd top off with saltwater until reaching your desired level.

 

[Goatonfly]

Like Diving said, If you don't have a ATO, just add salt water when you topoff everyday.

 

[gone fishin]

Do not use the sea salt you need salt made for a marine tank. Others have mentioned the ways to increase the salinity. I will caution to raise the salinity back up slowly. Fish can handle a quick drop in salinity than a quick increase in salinity.

 

[AlSimmons]

I would just let the salinity correct itself through evaporation.

 

[Sk8r]

Fish tolerate a DROP in salinity quite well. A sudden rise in same can kill them. Bring your salinity back up by topping off evaporation with salt water instead of fresh.

Marine salt is a compound of many, many minerals: read the label. Table salt will not do.