Is it safe to swim after adding hydrochloric acid?

It is safe to swim after adding hydrochloric acid to swimming pool. but in a small quantity like for a pool just a liter of dil. HCl (0.1N) . But if you use conc. HCl , then there may be chances of skin burn or blisters etc. to the skin.

It mainly depends on concentration. and amount of water is added.

DO NOT ADD conc. HCL to the water. There will the chances of bursting.