I can't figure out what's going on with my pool and would love to know if I should be doing anything beyond shocking according to Pool School. I recently noticed greenish yellow sediment in the low areas and now have a cc of .5. When we started up our pool it was sparkling clear and 3.5 is the lowest the FC has been this year. Last night FC was 15.5 and this morning it was at 15, still with .5 CC.
Here are my #'s: All measurements are mine except as noted
ph 7.4 (measured before shock)
TA 210 (I know! We have hard water in our town)
CH 275 (according to pool store)
Total dissolved solids 1200 (according to pool store)
According to the pool calculator, FC of 3 is the lowest it should get - and it got down to 3.5. I am using new reagents, but I'm not really trusting my CYA measurements. At pool opening CYA was below 20 (no reading), I added enough to bring it up 10, it barely showed after five days. I added enough for 10 more and a week later it showed CYA of 40. Now it reads about 32 and if I really study it I can still see the black dot. Pool store readings - which I never believe, were CYA of 125 in their high tech pool water analysis device and CYA of 70 with their tablet method.
More information: Last year we just could not get rid of the algae under the steps. We have the Innovaplas Walkway steps, which do not have openings on the sides. I was constantly shocking the pool (per pool school) and it seemed like we were always waiting for the chlorine to lower enough so we could swim and then it would need to be shocked again. It was very clean at closing with FC of 33 and Polyquat.
In Mid-May it was about halfway full (it lost water through the skimmer because of snow and rain accumulation on the cover). We filled it to mid-skimmer and set the pump up (with new sand) and it has been running about six hours a day. We did not brush it and we left it covered because we didn't want to deal with pollen and birch tree droppings until it was much closer to swim time (pretty late here in Michigan). From peeking under the cover, the water looked very clean and clear. FC was 6 after filling. When FC was about 5 I noticed sediment in the low areas/creases. I was hoping it was sand - FC levels were good and I didn't check for CC. When FC was at 3.5 I shocked it to a calculated 16 but didn't measure it afterwards, and left the pump running 24/7 while we went out of town for four days. We uncovered the pool yesterday when we got home. I scooped out about ten leaves that must have snuck in while we were putting the cover on last year and brushed it. Cloudy sediment drifted up while brushing. The pump is running on schedule, six hours/day. We haven't put the steps in yet. I scrubbed them with bleach, but it is not realistic to scrub every surface, especially since the assembly includes hollow tubes with bolts through them.
So - my questions are:
How should I proceed regarding CYA and Chlorine?
Where is the best place to put the steps (best circulation)? Any other recommendations regarding the steps.