Help with a newbie to salt!

Ok.. this couple was moving and didn't want to deal with transporting a tank in the move. It's a 20G with home-made landscape made predominately with sea-shells...
The water level was about 5 gallons low, probably due to neglect and evaporation. So I took a test and the Hydrometer maxed out at over 1.028 (highest the scale reads) and Salinty of over 38? So I so far have just added 2G of aged tap water. Next up? Bill
Oh it had one clown fish in there (far left next to the thermometer) and a suspected "croaker minnow"...No grounds keeping crew that she knew of... I'll check with a flashlight after lights out.

Salinty should be like 1.022 -1.023 hope that helps

Yea.. the meter tells me those numbers... but the water ain't cooperating!..LOL... I'm thinking if I just diluted the existing water, it might bring it down.

It will just keep adding water a litte at time checking each time
I would go a 1/2 gallon at a time util you get clos

Do it over a several day period so you don't shock the fish from the salanity change. Need to check ammonia and other parameters to maybe. Sniff the tank water if it smells like the ocean all is well but if it smells like funk ut oh. Oh and add prime to aged tap water as well

Oh and1.025 is a safe level try and aim between 1.023 and 1.025 is what tanks are normally kept at

Gotta use RO or distilled water or you will have the unpleasant surprise of red slime as well as a bunch of nuisance algae. Naked water like RO is best, tap has way too much weird stuff in it to be used for salt. Go slow with the salinity correction. For clean up crew you want blue leg hermit crabs and small turbo/astrea snails 10-20 of each, you will know when you have enough just by looking at the tank. You should hunt around and see if any of your lfs sell pre mixed salt water (unless you have an RO) For a tank that size its not worth messing with mixing your own salt if you can get it local. here RO is $.45 per gallon and pre mixed salt is $.99 per gallon to give you a rough cost.
Waterchanges are same as for fresh, 15% or so every 2 weeks. You should do one soon as you locate some water, if you gotta mix your own go with red sea salt, really good stuff thats always the same with each batch unlike a lot of the other salts out there.
What kind of light is on there? Old bulbs and wrong lighting can cause algae issues in salt.
I kinda like that shellscape! Its pretty cute!
Oh and DO NOT mix up or disturb that sand bed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! You do that and you will have massive problems!!!!!!! That is part of your filtration!!!!! To vac it just do a light sweep on the top to get the loose stuff, if you want but not necessary. I never clean my sand.

And that clown does not need an anemone, most are raised in captivity and have never even seen one. Nems can be a pain especially in a tank that small.

So tell me more about the setup!