This is what I would do. Test the sg
and make sure it is within 1.019-1.026. Check the temp and make sure that is ok.
1. Set up a drip with a air line. Make sure it drips only a few drops a sec.
2.place the clownfish I'n a bucket with the water from the bag.run the drip from the tank to the bucket.
3.turn off all the lights to not stress the fish.
4. Wait about half an hour.
5.place the clownfish in the tank and monitor them for about half an hour.
Just follow the steps and your fish should e ok for the night. As far as sand trust me it will all settle to the bottom In 24 to48 hours your tank will be crystal clear.