I bought a short-sale home last summer that features an AG pool (2yo liner). They had winterized it the year before and never took it out of hibernation, so it was a large pool of algae when unsheathed. 12 inches of visibility, tops. We had a pool guy come to explain the equipment (all tip-top, and there's even a bottom vacuum shark). He instructed us to pour giant buckets of chlorine in and keep the filter running non-stop, cleaning the filter non-stop, until it ran clean. This was tough going (took me a while to figure the "trick" to open the filter without my husband's brawn, so it couldn't be changed frequently), and then we went out of town for a weekend, and - long story short - after a few hundred dollars, it didn't look ANY better. (I tried flock, too, and didn't see any difference.) By that point, it was "winterizing time" anyways, so we decided to give up until the spring.
With the first freeze, the algae must have gone into remission, and I could actually briefly see to the bottom (!!), so I'm pretty sure that there isn't anything terrifically scary beneath the water, but lately it has been warm (in addition to other weird weather), and the green has turned less algae-like and more like chlorophyll. Thick, green, NASTY... maybe 3 inches of visibility, if the sun is right. I've searched this site, and it looks at least as bad as the "worst pool ever" posts. Surprisingly, it doesn't smell rank. Neither are there any apparent insects/ creatures breeding in it.
I will declare it a major miracle of chemistry if this water can actually be cleaned, but if it weren't for the liner it would certainly be cheaper to drain and refill than those expensive chemicals. I bought many bottles of bleach, having read that this can be a substitute if used at night. (I also have some algacide purchased for cheap at a hardware store closeout.) I see previous posts that have tackled similar problems. I guess my two main questions are:
1) It's going to get cold again, so I won't start my attack for a few months, but how long should this cleaning take? A week? A month? (Do I shock every day?) I need to know to plan my attack when we won't be going out of town so I won't be starting from scratch.
2) How much water could I safely drain the pool? I'd rather dilute it as much as possible. It's just so impossibly nasty.
I really appreciate your feedback and well wishes.