With such a small tank, I would just take all the livestock out, in a bucket with the current tank water, refill the tank with fresh correct 1.024-1.025 saltwater, and re-acclimate the livestock to the new water for a few hours with slow drip method. There's not a whole lot going on in your tank that would be too sensitive for this approach, and you don't have to worry about correcting the issue over the next several weeks/months with partial water changes. Wouldn't be any different than if you brought something home from another tank to put in yours.
Then you won't have to worry about any more variables with your current water.
EDIT: might be vague in description since i believe you are still newer, you wouldnt want to acclimate the livestock sitting in ALL 6 gallons of your current water, bag them up or leave them in enough water like if you brought them home from a store. And buy or mix enough additional salt water to top the edge back off after you acclimate and move them back in the tank.