As Watermom pointed out, DE filters clog almost instantly when live algae is present; you have to add enough chlorine to kill ALL before you are going to get adequate filter performance. With a gunite pool, there's no problem with high chlorine even if you have no stabilizer.

So do this:

#1 - Add 7 gallons of plain 6% household bleach tomorrow morning, and
#2 - Add 10 gallons of plain 6% household bleach tomorrow EVENING.

Meanwhile, if your filter has a valve with a "Recirculate" setting, use that, till the algae is dead.