I just moved in a home with a very old pool a month ago. Has been learning how to maintain the pool by myself; balance the pool water, clean the pool etc... Got a lot information from this site and really appreciated!
The last thing bothering me is the little black spots in the pool. I noticed that after I clean the pool a month ago; there was a lot of the debris in the pool when I moved in; it's a foreclosed home.
I thought that's black algae in the very beginning. I tried to rub it with chlorine tab and took some sample with fingernail, but none of that succeed.
Then I tried to rub the spots with the vitamin C tabs; but the black spot still the same.
Last week I shock the pool and brush the black spots with stainless brush in the morning and evening, but still didn't see any changes. Have no clues what to do next.. I attached some photos I took underwater this weekend.
FC: 9 (test this morning; a week after I shock the pool)
Calcium Hardness: 200
By the way, is above water safe to swim? My 2.5 years old wants to play in the water everyday. I stopped her for a week when I shock the pool.
Any advice will be much appreciate!