ok, 25,000 gallon above ground pool. Brand new sand filter. Been in the 90's here all week.
tc-put 5 drops of oto in tester water turned dark yellow almost brown with little red specks in it.
ta-put in 100 drops would not turn red just lite yellow color
What is going on! tested water 3 days ago with these results
Added 7 pounds cya. ph minus, 8 gallons shock