I ran across this image and just had to rant about it. This is so wrong this pond professional should be banned from building anything.
You will notice the image shows a bottom drain running to a skimmer via 2″ pipe.
1) Bottom drain should have 3-4″ pipe minimum.
2) You can not run a BD to a skimmer because the face plate has more area for water to enter the skimmer than does the Bottom drain. You will not get effective draw through the bottom drain.
3) If some tries to tell you this is correct, fire them immediately and save your self some trouble.
To do it right, Add a separate box/chamber for the BD. One drain, one filter system, one pump. Skimmer should have it’s own pump and possibly filters.
IF YOU ONLY HAVE ONE PUMP – run the bd to a line outside the skimmer and use a wye into the pump circuit but have control valves on the skimmer and bd lines so you can adjust flow (which is still not ideal since you can not really know the flow through each line.)
