I have a pool and a spa, using the same pump and filter. I do not use the spa often.
It appears that the four jets that fills the spa are having less pressure or volume compared to say six months ago.
Here is a picture showing what happens when I drained the spa (by opening the spa suction line valve to the pump), then refilled the spa with the water from the pool (by switching the valve on the return line from the pool to the spa). You can see the water coming out strong and reaching farther.

Today I repeated the same process, and noticed the water coming out is much weaker. It is a steady flow, but slower and weaker.

Does this mean I have a leak somewhere on the suction side or the return side?
I then drained the spa completely, then switched the suction side to come from the pool main drain, to the pump & filter then to the spa return line. Same result.
I then turned off the pool main drain suction line and opened the pool skimmer suction side, same result. Then I tried the pool cleaner side. I was hoping that if I were to notice a difference, it means one of the lines on the suction side may be problematic.
Could the return line be partially clogged?
Could the pump itself be getting weaker?
It appears that the four jets that fills the spa are having less pressure or volume compared to say six months ago.
Here is a picture showing what happens when I drained the spa (by opening the spa suction line valve to the pump), then refilled the spa with the water from the pool (by switching the valve on the return line from the pool to the spa). You can see the water coming out strong and reaching farther.

Today I repeated the same process, and noticed the water coming out is much weaker. It is a steady flow, but slower and weaker.

Does this mean I have a leak somewhere on the suction side or the return side?
I then drained the spa completely, then switched the suction side to come from the pool main drain, to the pump & filter then to the spa return line. Same result.
I then turned off the pool main drain suction line and opened the pool skimmer suction side, same result. Then I tried the pool cleaner side. I was hoping that if I were to notice a difference, it means one of the lines on the suction side may be problematic.
Could the return line be partially clogged?
Could the pump itself be getting weaker?