Eshopps HOB overflow issue

[SOGavity]

I've been using this Eshopps Overflow for roughly a year now without any issues. During my last water change, I cleaned the round filter that sits around the drainage pipe. But I've done this before without problems, multiple times. But this time the overflow isn't moving water fast enough. I usually run my return pump at 90% (I don't know technical terms). But now I can only run the pump at 35%. It's a HUGE difference with water movement. The u-shaped siphon does not have any air in the tube. I have not removed it at all, not even in an attempt to fix this issue because I doubt I will get it without air in the tub again. Setting it up to the point of no air bubbles was a nightmare. I do find though, if I move the u-shaped siphon a certain way, I can get it to move water faster, to the point I can get my return pump safely up to 85%. But a light tap on the tube causes it to siphon water slower. (It doesn't matter if I have the sponge in the overflow or not. Results are the same). Anyone with this type of overflow have any advice on what's going on?

 

[exnisstech]

I ran dual eshop hobs on my 180 for years and never had this problem. I never ran the pre filters because they plugged too fast. I had a basement sump with an external pump and flow was controlled with a gate valve and I never experience your issue. All I can think of is to make sure your return pump flow is consistant tho I'm not exactly sure how to verify that other than the controller read out. Also make sure a snail or some other critter didn't get in the pipe.

PS: I wouldn't worry about what % the return pump is at. Set it so the flow is not causing the overflow box level to get to high and not to low where it will draw air and loose syphon.