I have an Intex 20x48 Ultra Frame pool with a salt water system. I am very new to this and really don't know what to do...
After a couple of storms I've notices a discoloration to the bottom of the pool. It is patches and even some lines (about 6 inches wide). It doesn't feel any different, it is not slick. I have scrubbed it nothing changes. My pool is crystal clear. You only see this discoloration in the evenings when the sun is going down about 6 or 7 o'clock. During the day with full sun you don't see it at all. Is this algae? Is it possible to have algae or mold under the pool (like between the tarp and the bottom of the pool)? I have to admit I did add 8 oz. of Algaecide, it did not make any difference. I'm a little worried now about my son getting in the pool because of the Algaecide (I'm a worrier).
Also I am confused about my levels. I run this salt water system 8 hours a day (filter 12 hours) and my numbers are always low.
Free Chlorine usually 0
Total Chlorine usually 0
Alkalinity usually 40
pH 6.8 to 7.2
Total Hardness 50
As I said my pool is crystal clear, my son's skin and eyes are no way irritated like in a public pool (he wears goggles and the fill up with water and he doesn't even realize it). Are these numbers OK?