Clontarf's victory at Castle Avenue was achieved with relative ease, with Alan Dignam, Declan Quinn and their overseas number eight Ben Gissing making the hard yards.
Daire Higgins went over after just 30 seconds, and although Ballymena outhalf Peter McIntosh managed a penalty on 13 minutes, Clontarf went further ahead when Gissing fed off outhalf Mark Woods to score under the posts after Quinn had spilled in an earlier move
McIntosh made it 10-6 at the break but Clontarf finished things off when Higgins and opposite wing Ollie Winchester crossed for tries. Both were converted by Dave O'Brien, who added a penalty before Ballymena responded with a converted Steve McConnell try.
Clontarf's Eadon Burns went over in the final moments, with O'Brien again converting.
CLONTARF: D O' Brien; D Higgins, A Reddan, J Downey, O Winchester; M Woods, M Walls; A Clarke, M Kennedy, T Foucher, A Wood, D Sheehan, A Dignam, D Quinn, B Gissing. Replacements - E Burns for Walls (79 mins), P Ryan for Woods (76), W O'Kelly for Foucher (51), T Kearns for Kennedy (58), D Moore for Sheehan (60).
BALLYMENA: S Young; N Beddows, H Swift, G Mitchell, A Maxwell; P McIntosh, B Ree; N Mc Kernan, A Gamlin, B Young, P McBride, M McCullough, D Patrick, J Taggart, D McCartney. Replacements - S McConnell for Mc Kernan (60 mins), D Topping for Mitchell (54), R Kernohan for Gamlon (60), M Mc McComlin for Patrick (64), J Cuppit for Maxwell (71)
Referee: S Flannery (Munster).