An update.
Took the pool cover off April 29 to reveal a green swamp. Previous owners let it go. I started with skimming off at least 3 to 4 bushels of floating leaves. Since I couldn't see the bottom, I then proceeded to "scoop" what I could from the bottom of the shallow end. Took out another 2 bushels.
Had local company come for pool opening on May 2nd in a snow storm no less. They shocked with 32 gals liquid chlorine and added algae and metal additives. Lots of foam and leaves raising to the top. Skimmed another bushels of leaves from the surface and emptied the skimmer baskets several times. The bottom drain seemed plugged with leaves as that line wasn't pulling much water.
The multi-port valve was leaking. It was replaced. The sand in the filter needed to be replaced. I cleaned out the old sand and replaced with new on the following Sunday and got the filter working.
With the pump now running, I purchased a leaf vacuum and went over the entire pool taking out another 2 bushels of leaves. Again of of this was blind work since I couldn't see the bottom. I focused on the deep end in an attempt to lift leaves from the bottom drain and free it up. It worked and the bottom drain began flowing water through. Monitored both skimmer baskets and pump basket several times each day and emptied the same. Backwashed the filter when the pump pressure would rise to 10 lbs over normal operating pressure. So far I have backwashed about 6 times on the past 3 weeks.
We have been trying to keep the FC at least at 10 ppm in order to help clean and clarify. pH has been relatively easy to control. The pool responds to soda ash as expected. Alkalinity and CH were high but seem to be coming down as we get the rest of the things balanced.
We started seeing the bottom of the shallow end - 3 feet depth - about a week ago. It has steadily improved in terms of clarity but up until we treated for phosphate, it was always cloudy. We also ran into high TDS so I drained about a foot from the pool a week ago, filled back with fresh water and shocked with another 8 gal of liquid chlorine. Helped some with clarity but still not progressing as quickly as we wanted. Turned out we had high phosphate level and I just finished treating for that yesterday. 3 days ago I added the Phosphate Removal, ran the pump for 18 hours, turned the pump off for 24 hours. Yesterday morning woke to a clearer pool with some sediment on the bottom. Still couldn't see the bottom of the deep end but could see farther down - about 6 feet. Vacuumed to waste at the bottom of the deep end by feel until skimmer started sucking air. Drained some more from bottom drain. Refilled pool - about 6 inches and then vacuumed the shallow end to filter. Backwashed filter before, during and after vacuuming. We had a storm blow in so I had to put everything away.
Woke this morning to a pool where I can see the deep end bottom drain. Not totally crystal clear but I can see the drain. Tests as follows:
FC - .5
CC - .5
pH - 7.5
Alk - 150
CH - 380
Added 4 gals of liquid chlorine (12.5%) at 7:30 am. Will test again at noon to see if we have acceptable FC levels.
It has been quite a journey. Quite an expensive one at that. Far more than expected. Lesson learned - never put a pool away green.