These are the places that I used to swim and practice swimming.
http://zimantra.com/index.html Day pass = 600 LKR, Mothly 5000 LKR Batharamulla.
Nugegoda Anula Vidyala, open only after 4:00 PM for outsiders. Chargers 150 LKR for pool per one hour , 250 LKR for couch for a lesson.
Nugegoda Sanhida leasure center.
pool membership 12,000 LKR annual, Adddress Address: 247/6 Etul Kotte-Mirihana-Kohuwela Rd, Nugegoda 10250
150 LKR per hour for adult. 200 LKR for couch.