There is no direct water connection between pond and filter. The water is sucked out of the filter and dropped into the pond thru a TT, so the water can't siphon back.
The water from the pond then overflows onto the screen and falls thru it, pushing the waste ahead of it. The screen isn't submerged.
email me at
bil_wight@ntlworld.com and I'll send you a diagram. Put something about filters in the subject line or the email will get deleted with the spam.
The idea is that if the screen does fill up and clog, the water will overflow into the filter and then the crap would be caught in the static K. No risk of overflow.