HOB filter placement: intake or outflow location

[JenTheDroid]

I have a 20 gallon long. I bought the tidal 55 since the 35 doesn’t have an intake tube. I originally had my filter on the right corner because the outlet/return flow was on the right and was worried that was keeping everything from getting to the skimmer. I was planning on putting it on one side of the tank until I realized it doesn’t really work with my light. I left it for about an hour and realized my fish weren’t really swimming around either. I move the filter to the back again and put it mostly in the center and my fish are swimming around now problem now. However, I’m not sure if it is the intake that should mostly be centered or the return that should be centered. If the intake is centered then the HOB isn’t really centered because the filter is 8 inches and the intake is only about 2 inches of that. 
 

I know I’m seriously overthinking this but I’m just trying to figure out what’s best before I get a new lid. 

[ScottieB]

I get it (i think). No problem. I think the tidal 55 is pushing around 200+ gallons/hour. So no matter where the intake is that thing is cycling your tank volume every few minutes. Thats prob with the blue knob turned up all the way. 

I would go with whatever fits your lid and whichever is more aesthetic to your tank viewing or what ever the fish seem to tolerate best.  On a side note, Ive seen it on the short side of a 20L set up like a peninsula. Honestly there's really no right and wrong or answer.