Bell Siphon for Aquaponics

Simple bell siphon for an aquaponic system I set up in my balcony. It has been great to propagate cuttings too. 

The first prototype was printed in PLA but after a few months, the bottom part broke, so I printed it again in ABS.

The minimum size hole in the planter is 15mm diameter and a maximum is 29mm diameter. 
The fitting that connects to the draining tubing is 13mm OD – I'm using a 13mm ID tube.
I have had issues with the pump flow not being strong enough so I added a reducer that turned the draining pipe from 9mm ID to 6mm ID.
I have also added a gasket to the bottom of the siphon to avoid leaks.

If you want to modify this design in any way, here's the onshape link: https://cad.onshape.com/documents/e7dd578512e00a82287249fb/w/b4d4530cc2b27470b3e647ca/e/b0629285d10ba4322fff8e88