I made my own durso pipes for my 125 marineland dual overflow dt tank. the bulk heads are 1 inch and the durso pipes i made are 2 inch. my problem im runing into is that I have to remove the durso pipes to get it to start siphoning the warter I have adjusted the water flow from the return pump to practically nothing. I got to the point where I have to remove the durso pipes real quick to get it to start siphoning the water. then it's fine. the bulk head are im including a picture of where I think the problem is on the durso. the onlyl difference I d o have a cap at the top where the picture doesn't have one. the bottom goes into a one inche pipe and the top is 2 inch. could that be my problem? I have checked for blockage and removed them and cleaned them. nothing blocking the water flow. any ideas would be helpfull. thinking on redoing it and going from 1 inch pipe to 1.25 inch. two inched pipes might be to much.