first of all, the knife hole is just to break up suction in your return hose in the case you lose power and it drains back out into your sump. There is suction created when you have a sump and the water drains backward from your tank into the sump from two places, one is the overflow box and the second is the return hose from the sump. Since it usually hangs lower than the overflow box, the water keeps flowing into the sump until it reaches the end of the difuser. Here is a pic:
See how it sits BELOW the overflow box? the water is supposed to stop draining during a power outtage at the overflow box, but if you do not put a hole in the black hose, about two-three inches above the end of the hose, water keeps getting sucked from the tank back into the sump. The hole could go all the way thru, I guess, but just needs to pass thru the plastic into the hose so the suction gets broken when the water level goes past the hole you punch. Hope that makes sense.
As for your bubbles, they won't hurt anything. Second, post a pic so we can get an idea of what you are talking about. It could be that there is not enough water in your sump and that what goes into the chamber with the return pump is so agitated to begin with, it is creating bubbles. Does the end that goes into the tank look like mine, with a difuser? that is to help with bubbles as well. Post a pic.
-Dr Marco :sfish:
See how it sits BELOW the overflow box? the water is supposed to stop draining during a power outtage at the overflow box, but if you do not put a hole in the black hose, about two-three inches above the end of the hose, water keeps getting sucked from the tank back into the sump. The hole could go all the way thru, I guess, but just needs to pass thru the plastic into the hose so the suction gets broken when the water level goes past the hole you punch. Hope that makes sense.
As for your bubbles, they won't hurt anything. Second, post a pic so we can get an idea of what you are talking about. It could be that there is not enough water in your sump and that what goes into the chamber with the return pump is so agitated to begin with, it is creating bubbles. Does the end that goes into the tank look like mine, with a difuser? that is to help with bubbles as well. Post a pic.
-Dr Marco :sfish: