When you say years... how many? I don't have (or think) I have a mosquito problem since water is flowing well and did have frogs.. so was thinking the mosquito tablets
I think that the life of the liner exposed to Chlorine would be determined by the solution strength of the Chlorine.You would not need the same level of Chlorine ass used in swimming pools since the control of aquatic pathogens would not be of the same level of importance as in a human immersion venue.
Mosquito dunks, either tablet or granular will control mosquitoes.
Update: Did some quick research. It seems-
-that Chloramine causes greater degradation in EPDM than Chlorine.
-that low pH and high temperatures support higher degradation. (test case in Japan revealed a usable life of about 3 years at high 45C-65C temperatures when exposed to Chlorine treated city water).