I would like to pass on a couple of ideas about the topic at hand.
First, with all coating be it paint over wood, urethane or epoxy on concrete floors or even mortar for tile laying, the substrate preparation is the key to a successful installation.
The preparation for concrete for epoxy should include the following:
1) A clean concrete floor.
Muriatic, or any acid for that matter, does not remove oil and grease. You should seek a product made specifically for degreasing. Follow the instructions and remove all traces of the degreaser and lifted oil or grease when finished.
2) A method to create surface profile.
Muriatic, or hydrochloric, acid will create surface profile, however, if not strongly diluted, the fumes may cause surface rust to appear on any ferrous metals. Further, if the applicator doesn't have appropriate respiratory protection, it could be harmful to the applicators respiratory system.
If you are going to use muriatic acid, you must also neutralize the acid with a base like baking soda. I would think that in California there are some fairly stringent rules about muriatic acid run off. I would strongly suggest that you don't use muriatic.
A better method to create surface profile would be to shot blast the concrete. I would imagine you could find a contractor in your area that would shotblast the concrete for you. Either way, with muriatic or shotblasting, you are generally looking for an 80ish grit sandpaper feel to the concrete.
Oh, and even though the shotblaster will vacuum the concrete as it blasts, you will still need to rinse the floor of dust.
3) Properly cured concrete.
Properly cured concrete generally reaches 97% of it's compressive strength in seven days. Most commercial floor coating manufacturer's would likely say the barest minimum cure time for the concrete prior to the application of coating would be 28 days, but I like the idea of giving the concrete plenty of time to cure.
4) A dry substrate. Maybe.
Most one hundred percent solids epoxies are moisture insensitive and can be applied to damp concrete. As a flooring contractor, I don't usually like to apply any coating over damp substrates, but sometimes, there is that need. Of course, whatever product you choose to use would drive what condition the concrete needs to be in. I would choose dry over damp.
5) A properly functioning vapor barrier.
If you have no vapor barrier under your concrete, you run the risk of moisture drive to the back of the applied epoxy and the resultant de-lamination. If you don't have a vapor barrier under the concrete or you don't know, there are products that can be applied to the top of the concrete prior to the application of epoxy that will block any moisture to the back of the coating.