I closed my pool on Monday, 9/28/2015. I gave up trying to get a chlorine reading after spending 3 weeks and hundreds of dollars on shock, 3" tablets, muriatic acid, liquid bleach, and draining the pool 40%. I don't give up easily so today I peeled back the cover and took another water sample. No change: FC=0, TC=0, pH=7.4, ALK=100, Calcium=200, CYA=0. I even tested for ammonia with my fish tank test. .25 ppm. I believe my sand filter is part of the problem. It started to fail in mid-summer and I have not been able to clean or replace the sand. The sand was last replaced in 2008. My equipment is in my basement which includes a one bedroom apartment and nervous tenants. Now that the pool has been winterized, i.e., water level is 6" below the skimmer, should I try to stabilize with liquid stabilizer/conditioner followed by liquid (10%) bleach or just wait until spring? The water already has a green tint and visible algae on one side. I fear the enivible swamp water next spring. If I try to correct it now, I estimate I will need to spend $165 on liquid stabilizer (4 gallons @ $25), liquid bleach (4 gallons @ $5) and algaecide (1/2 gallon @$45). What do you suggest I do?