Low suction pressure

[waterbear]

When you add DE powder you mix it into a thin slurry in a bucket first and then slowly pour it into the skimmer, correct?
If not that could be the problem. DE can block pipes and form a cement like obstruction if added improperly.

[Pool Clown]

I noticed that in your post, that you keep stating "skimmers" as in two? That could be why you cant get good suction for your vac. Can you isolate the skimmers (turn one off)? If not, a tennis ball, or a threaded plug in the size of the skimmer, 1 1/2" or 2" works best.

If you have the short pine needles, they will get their way to the impeller to clog/block it. I've never been able to stick my hand into the pump to feel the clog, you have to either take the pump apart, or get a mirror and look that way for the blockage. The mirror is easier than taking the pump apart.

Another note: If you have a variable speed pump, or a two speed, you will normally get a bubble in the pot basket (with low speed(s)), especially the Jandy e-pump, the pot is way too big to begin with!