Problems vacuuming

I similarly just opened up my pool last week, and found when vacuuming suction dropped very quickly. I'm new at this, so I don't know if I was doing things right, but I ended up vacuuming until suction dropped, backwashing out the junk, then continuing to vacuum (without adding fresh DE). I repeated this about 8 or 9 times, as I had a lot of gunk on the bottom of the pool. Then I added fresh DE, but still found the pressure about 10 psi over what I started when I first opened the pool.

Since my chlorine was down, I also added liquid bleach, with a little bit directly to the skimmer. That did the trick, I noticed the next day, the pressure dropped substantially (about 7-8 psi), and I got plenty of suction when I attached the vacuum head. I suspect there was an algae bloom in my filter (from what I sucked up), and the chlorine shocking cleared it up.

Wait for more experienced minds, but just letting you know, adding a little liquid bleach to the skimmer did the trick for me. Of course, if you have no flow, that probably won't help much.