HK$3,000.00 budget !!
Aquatica on Alona Beach would be my choice. Large non-air con room is more than adequate. However, the salinity of the tap water would be a course of concern for some people. Most resorts drawn the water from deep wells........
Alona Beach is NOT really suitable for swimming!!!! Long sea grasses with lots of sea urchins. Pretty painful if you step into one of those.
Excursion to Chocolate Hill in dry season shouldn't break your budget.