Hi guys,
I've been having some issues with my dual flush toilet. The toilet keeps filling after every 20 min or so. I then turned off the water supply and left it overnight. In the morning the tank was completely drained. I'm guessing it's some kind of seal between the tank and bowl but I have no idea how to disassemble the components in the tank. Where is the seal located? Where is the flapper? Any thoughts would be appreciated. Thank you

My guess is a bad bottom seal, there is no flapper. You have to remove the center part to get to the seal which is on the bottom. Push down slightly and twist to the left. It will disengage and when you pull it out you can see the seal.