I have 2 or 3 of those laying around, hate them. I found the easiest for me was to assemble the filter "dry", put the lid on out where you can make sure the "standpipe" is aligned with the hole in the lid, then fill slowly through one of the holes in the lids, attach the hoses and turn on. Make sure you remove the hoses after you take them out of the tank or they will siphon the water out of the tank. I don't know if it will help but that is what I found to work for me.