my pump is always on, and it was brand new last summer, i'm not sure what the filter PSI is, my gauge is broken, it used to run about 10-12 PSI when it worked, but i just bought 2 new paper cartridge filters, and we were vacuuming daily during the fight with a re-chargeable vacuum and not vacuuming thru the pool filter.
Everything is back to normal now, I'm not losing ANY F.C. ppm at night and only 3.5 during 14 hrs of daylight. The gray gunk has stopped collecting on bottom too!
Are you saying it might not have been that little strip of algae? because as soon as i scrubbed that away i was passing the OCLT the next night, even though gray gunk kept settling for a few days after.