Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I would not leave it unglued.
This is more of a suction sort of set up, not pressure.
If it starts to leak it will leak air into the pipes, perhaps stopping the siphon.
I also agree with the above: Either connect some tubing to get through that tight spot, or else add in enough unions to be able to take it apart. I have several tanks and a pond that switch back and forth between rigid PVC and flexible tubing and have not had any problems. I have several set ups with unions, and these are really helpful, in the right place.
The tubing barbs x PVC fitting with a hose clamp is a little harder to take apart, but put some vegetable oil or vaseline on the inside of the tubing when you are putting it together. The union is a bit more bulky, and I find pliers or a plumber's wrench is helpful in taking it apart.
Either way, put these junctions out in the open where you have access to them with both hands. Either above the tank or inside the cabinet.
Alternate: Remove enough water from the tank to slide it away from the wall enough to make the system work with glued PVC.