Backyard Aquaponics
A place to discuss aquaponics

I have an ibc tank awuaponics installation,
I build my siphon, with media guard, it work perfect for a couple of days.
Today i stopped the pump opened th siphon it was full of media.(i use hydroton)

How can i prevent the siphon filling with the stones?

A pic will help. Are you using a media guard to stop the hydration entering the syphon? If so the holes must be too big letting the stones in.

...or the media may be floating and lifting the media guard with each F&D cycle.

I have been fighting this same issue all weekend. I found three things to be true: 1. The broken pieces of hydroton were small enough to pass/plug the holes in the media guard and lodge in the bell siphon holes. 2. The media guard was floating during the flood stage (because the hydroton floats) and letting hydroton under the guard. 3. A piece of fiberglass screen and a rock seemed to solve the problem.
My bell siphon was also floating (so it would not start)before installing the high tech rock on top. I also found that the airspace difference between the center drain post and the bell siphon was critical to getting the siphon to stop. With too much air buffer it seemed to slow to a trickle and never fully stop. Less than an inch difference for my system seemed to work.
Hope this helps.