Opened a very dark green pool this year. Probably had some unresolved issues at closing.
After adding algaecide (28oz of Poly 60) and chlorine (liquid from carboys), and vacuuming and brushing several times over the last few days, the shallow end is getting clear, but the deep end is still pretty dark. Any way to tell what kind of algae it is?
When vacuuming the debris the day after I put in the algaecide, it looked like it was just coming back into the pool through the return. I have a sand filter and had the sand replaced last year. I vacuumed to waste which I think helped, but I'm wondering if this indicates a problem with my filter? Also after running the filter for a while, I notice that debris seems to pile up under the stream of water from the return in the shallow end. Finally, after backwashing yesterday, it took a little while for the pump/filter to return to normal pressure and the water from the return to stop bubbling/surging. Any thoughts?
My pool: approx. 20,000 - 25,000 gal free form vinyl liner.
My chemicals: CYA was zero at opening, but I added about 4 lbs to my pool. Waiting for reagents from TFTestKits. I'm maintaining FC at 3 - 5. pH is about 7.4 - 7.6. TA is 70.