I try and do it every day but I have a small PVC tube and vinal tubing connected to my manifold. But most people try and do it weekly with a Turkey baster or the like, If they need to.
Until I got enough flow going this was a constant frag killing problem. As soon as my flow got right I noticed it had stopped happening. Of course I run 3 MP40s in a 180 and I’ve played with the programming to make the swings in water direction as extreme as possible (long pulse changing direction once a minute). I may add a fourth.