I feed reptomin sticks but I sink them for my two. I break them into small sections with my thumb nail, drop one in the water and push on it so it goes under. Usually that's enough for it to sink. If not I use my finger to flatten it against the tank glass so any air goes out and then it'll sink, you just need to make sure you do that before the pellet gets too soft or else it'll just squish into a million little particles.