First thing is to double check the water your getting from the lfs and make sure it's actually low.... You might want to consider bumping your salinity level above the 1.023-1.024 level as you had stated. You can run higher, but I know that is what text book states..... What type of hydrometer are you using to test salinity? If you haven't already I would suggest into purchasing a refractometer will give your more accurate reading than the swing arm type hydrometers.
To raise your salinity you would just need to add a little bit of salt at a time and check the salinity. I say a little since of what you said the initial reading from the lfs is. You won't get an accurate result right away, that is why people usually let their water change water sit at least 24hrs before changing, and there are other reasons as well for that too.....
Last if the lfs isn't charging you for the water keep getting it from them but you might want to consider purchasing and RO/DI unit and make your own water... Will pay for itself down the road.....
Add a little salt at a time to increase your salinity
