Septic effluent pump question

Sorry did I miss the septic section? I dont see one. This section looked close based on my problem.

Problem: Septic sprinklers don't push as hard as I think they should. Comparing to my neighbors.

Details:
My Pump tank has a submergible mid intake stainless pump that drives 3 sprinklers in my back yard. Since I moved in the 3 have never really worked well. I replaced all the heads with the purple septic heads and pressure checked the pvc. So there’s not a leak anywhere underground.

Inspecting the pump I noticed the pump is down in a pvc tubed there is a 45* cut in the bottom to let water in. However the pump barely fits down the tube so there is not much space to let water so I figured the pump was overtaking the water input. See pic.



So looking around online I can't see any reason that green tube is there. There is also a larger tray on the bottom to keep the sludge away from the pump base.

Now, I removed the green tube, inspected the pump, looks good. But when I run the sprinkelers without the green tube it spray water out the side. This strips up al the stuff I the bottom of the tank too. So I'm thinking someone put the tub on to control the side jet and band-aid the situation. See video.

Should the pump do that?

 

Thanks, I’ll pull the pump and inspect for a hole

cooling shroud? The pump is full Submergible, seems like open water would be best no? Also the intake is in the middle. Seems weird to me. The entire pump is fit down inside the tube

pump looks like this one: