Upon removing the cover, I was greeted with 12,000 gallons of dark
green water that was once my swimming pool (24' diameter, 48" deep,
above ground). I was anxious to crank up the new pool filter & clear
this mess up, and in no time, the 1 hp pump was hard at work. Three,
no make that 4 bags of shock went into the pool in a frontal assault
against the green invader, and the filter ran all day. By the next
morning, the green was significantly lighter, and in went two more bags
of shock. By midday, we were getting somewhere. The green was almost
completely gone, replaced by a dense but translucent whiteness. A thin
scum of dead algae covered the surface, and patches of foam floated
around. I left the filter running all day; but saw no improvement by
nightfall.

My new pool filter is a cartridge filter, a Hayward Star Clear, 175 sf
filter area. It replaces an old but reliable Doughboy DE filter.
Because it's my first cartridge filter, I have no frame of reference
as to what to expect in performance. I know that cartridge filters
allow smaller particles than DE. Clean and fresh, the filter started
off at 6 psf pressure, and after running all day, it's only up to 8
psf. That's a good thing as far as I'm concerned, because one of
the reasons I abandoned DE was how often it would require backwashing
under these circumstances. It's also why I bought a larger filter
than I ought to need. On the other hand, the pool is still cloudy, and
time between cleanings doesn't matter if the filter isn't going to
clear up the pool.

So, for all you pool experts out there, I have a couple questions:

I realize that given the seriousness of my original algae problem, it
isn't going to clear up in a day, but inasmuch as neither the water
clarity nor the pressure gauge seems to be changing significantly, is
this normal for a cartridge filter? Are they slower to filter the
water as well as slower to clog?

I have taken the cartridge out once & hosed it off, and I paid no
attention to up or down when I put it back, assuming they were
interchangeable. Should I have checked?

On a different issue apart from the filter itself, I am getting a
steady stream of small bubbles with the return water that is
contributing to the foam on the pool surface. Where is this air coming
from? The basket gasket? The impeller gasket? It's not so much
it's a big deal, but it's nagging evidence that something's not
sealed properly.

TIA,
Joe F.