I have several issues to battle with my pool and i need to know what to address first so i can effectively clear my pool. i have an inground, sand filter, 21,000 gallon vinyl liner pool. haven't been able to get a good test kit yet, so having to use the strips to test for cya, which is 20. have been using bens chart to get the chlorine levels suggested to fight the green and it has worked. it still has a green and dingy tint to the water and the deep end is cloudy, but i can see the bottom. when i opened, the pool had brown stains and i have checked and absorbic acid will bring the stains off. i use well water to fill my pool so i know i am putting iron back in the pool as i am having to add water because i am vacuuming to waste. so what address first...i know i need to use the absorbic acid method for the stains, i need to continue high levels of chlorine to clear the green and i need to use the metal out to get rid of the metals in the pool...but what do i tackle first??? please help advise me. thanks!