I do something like that.
Going backward to the direction of water flow:
Down from filter to a PVC Tee.
Tee has short pieces of pipe and then more Tees. Each of these are aimed up, and have a short piece of sponge over it. The last in the line is a 90* elbow.
Longer tanks get as many as 4-6 inlets. Smaller tanks usually get 2-4 inlets.
The intake is as centered as possible in the tank, on the back wall. Pipe is sized to fit the filter intake, but after that first Tee can be reduced.
I do not use any glue inside the tank. If it leaks, where is the water going to go? Into the tank! ... is that a problem? Leaves the whole assembly more adaptable.
I keep all the inlets quite low. A lot more dirt on the bottom of the tank, and I do not need the 'skimmer' effect of high intakes. Still, it does need to be above the substrate. The substrate can get into the sponges, especially if there are fish that dig.
This works really well for river tank set ups. The outlet (Filter or power head) would be at one end of the tank and the inlet at the other, per the article at www.Loaches.com
Life in the Fast Lane.