[cabmandone]

Amazing what the right tool for the job will do isn't it?
Now that you're at this point, don't use a pressure washer to rinse. With the sealer all but gone you'll drive moisture into the pores of the concrete if you use a pressure washer. So if you're going to etch, rinse with a hose and as I mentioned before, you'll want to use a baking soda/water mixture to neutralize the muriatic acid. I was told when I did my floor not to etch if using a grinder. The concern was the acid leaving a film on the floor and having areas where PH was higher. Don't know why PH was a concern but must have had something to do with adhesion.

Also, when rinsing the floor, pay attention to how it acts when hitting the floor. If the sealer is all gone, you shouldn't have water beading.