Pool return jets

[mrjetson707]

I have 2 questions about return jets. First of all, how many do you really need? I have an odd shaped pool, about 11,000gal and 2 return jets. there's also a 3rd return that doesn't work. not sure if is old and abandoned or if it's clogged.
2nd question: does it matter if the return jets have those eyeballs on them? mine are just an open pvc pipe. the 3rd return that doesn't work does have threads so I'm a little confused on what's going on.
I've attached 2 pictures. the threaded one is the return that doesn't work. we are replastering in a couple months but I didn't bring this up to the contractor as I just kind of realized this. I think it could be an easy fix but I'm not sure exactly what needs to be done

 

[mas985]

Is it possible that the third return was for either a pressure cleaner or a suction cleaner. Is there abandon plumbing on the equipment pad?

As for the eyeballs, they are useful for directing the flow for better skimming. However, if you don't have an issue with skimming, then maybe you don't need them.

 

[mrjetson707]

Is it possible that the third return was for either a pressure cleaner or a suction cleaner. Is there abandon plumbing on the equipment pad?

As for the eyeballs, they are useful for directing the flow for better skimming. However, if you don't have an issue with skimming, then maybe you don't need them.

I don't see any abandoned plumbing. it's just odd. I have a feeling it is for a suction cleaner and its clogged and doesn't affect anything because the other 2 are closer to the equipment so they get all the suction. my best guess