I've been having trouble keeping my chlorine up, and I treated with ascorbic acid earlier this week because of a stain on the liner (my liner is blue and it looked green; so I'm guessing iron, but I don't know where it comes from. I'm not on well water; I first got the stain last year...). My CYA has remained very low, though I've added five or six gallons of liquid stabilizer since opening the pool about four weeks ago. The I'd been trying to take care of it with my SWG and chlorine, but I finally had the company that put in my new pump take a look. They added chlorine, and I noticed the water was cloudy. Last night the Ph was inching up to 7.7 or 7.8; so I added acid and got it back to around 7.4. Today I tested, and the chlorine was still low (about 1). This afternoon I shocked the pool to about 16 as my CYA was around 37 according to the pool company's electronic gadget, and within an hour it was clear but green. I'm guessing I need a metal sequestrant. What would be a good one, how much do I need, and do I need to retreat with ascorbic acid first?