My 72 year old (female) Friend had an algae problem caused by a broken pump motor and a lot of leaves. I replaced to broken motor, cleaned to DE Filter, got as many of the leaves out as possible without being able to see the bottom of the pool. I Shocked the pool and ran the pump until my friend turned it off because she was afraid the pressure was too high (40 psi). I do not live close so I have been traveling to her home every day for about a week and a half now, when I leave each time after cleaning the filter again, using Green to Clear, Shocking several times the pressure will read around 15 - 20 psi and then begins to climb to around 40 psi within just a few hours. I am very frustrated now, I have cleaned filter 3 times, backwashed so many I can't count them and even soaked the filter for 24 hours in a trash can with a solution of water and muriatic acid. The pool water has gone from dark (swamp) water to light green cloudy. I spend 2 hours there today, cleaned filter baffles by removing them one by one and spraying down with hose, recharged the filter with DE, added 3lbs of Shock (35000 gal) after I left she called me 2 hours later and told me the pressure had risen to 40 psi again and she is shutting it off once again. Does the amount of algae in the pool rise the psi? Is there anything I can do to keep the pressure from rising so fast so she will leave the pump running long enough to clear the algae and get the water to a clear/clean? Any and all help will be appreciated.