I am trying to get a more circular flow in my blue blob. I figured it may help the languid flow of my 1Kgph pump.
So, step one, mark the 12 o'clock position with the discharge cap screwed on tight. A scratch with a screwdriver does just fine. Also, time to decide at what angle you wish the flow to be directed to, my choice was 4 o'clock. This should get things moving in a circle, as well as point the discharge towards the bottom to mix things up.
I removed the cap and headed to the hardware store plumbing dept. based on the size of the central bump, I picked up an 1 1/4 "street" 90deg elbow. "Street" means one side of the fitting is female, the other side is male. The male side is what I used for the discharge, since the ID is smaller. Overall that ID is still larger than the stock discharge cap hole.
Back to the shop, I used an angle grinder to sand down the center bump until it was just shy of completely gone. I secured the fitting to the cap from the inside using masking tape. I used a 2 part epoxy to glue the parts together on the outside. After the exterior epoxy cured, I removed the masking tape inside, used more tape to protect the threads, and applied PVC glue to the inside. I gooped it in there fairly heavily, just pas the cap into the fitting. I turned the fitting on its side and rotated it so the excess cement built up where the fitting and cap mate.
I installed it a while ago, and it didnt blow apart! Time will tell whether the flow will work out better with the directed discharge. It was a cheap project, the fitting and cement cost about $5, the epoxy I already had.