Plumbing question

[beefcake]

I've been setting up my new tank using an Eco-system filter. The manual recommends the layout shown below. I was worried about a siphon effect if the power ever goes off and was wondering if the "back-up flow" line would solve this problem. Thoughts ? TIA !

 

[beefcake]

here it is

 

[p_apac]

just make a small hole in the top of the return line to break syphon. or just make the return at the top and close to the surface so it will drain a little but not much

 

[beefcake]

If I make a small hole at the top of the return line wouldn't water jet out of it even though it's small ? How small are we talking? Like a pin size hole ?

 

[sebae0]

just below the waterline i think he means, both my retturns are flexx hose fitted to a plastic return that hangs in the water. right below the water line i drilled a small hole so if the power goes out the water will start to back siphon and when it gets to the hole it sucks air in and breaks the siphon.