Maybe use some black plastic canvas (for crafts) to block the K1 from escaping the OF teeth. Easily cut with scissors and endless uses in the hobby. It comes in various hole sizes to keep that pesky K1 where it's supposed to be.
Can you route the drip line so it just fits through one of the OF teeth but is not visible inside the tank?
Looks good! I figured the K1 would just escape through the egg crate also but looks like it is working.