It is perfectly safe, and rather expensive for what it is. If you're of a mind and wanna skip the sitting out step, go to The Chemistry Store dot com. Buy the sodium thiosulfate. Dilute the crystals to a 3% solution, and use that at the same rates as pre-made dechlor.
You're welcome, now you've got enough dechlorinator to last you for life. Or, enough to dechlor a whole pool at least. :D