Debris and Pressure

[michealcell]

I'm having an issue with debris in my pool and I don't think the filter is filtering it or maybe something else is going on. I opened the pool 2 weeks ago, got pool vacuumed and cleaned up, the water looking nice, chemical levels where they should be; but I was still having 2 issues: 1) there was tiny debris still in the water (too small for the net) and 2) the water pressure seemed low, there were things floating in the skimmer and it didn't seem to have enough suction. So I read online and thought the issue was either the pump or the filter. So I checked the impeller but it didn't seem blocked and moved just fine, which left the filter. It had been a few years since the sand had been changed, so I went about changing the sand in the filter.

Now there seems to be more pressure but there are still things floating in the skimmer and it doesn't seem to be sucking it down into the skimmer basket and the water still has debris floating in it; is this normal, as I seem to remember there being a vortex in the skimmer that would suck everything down to the basket? The PSI on the filter stays around 13 or so, which I'm not sure if this is normal or low, as the gauge that came with the filter broke years ago and I just replaced it when I changed the sand. I've read the other threads and really don't have any other ideas on this. Thanks!