I have an inground 20' x 40' pool, sand filter, in-line clorinator and a Nature 2 cartridge. Pool was clear until early May the started turning green. I added tablets to the clorinator and used 3 1# packages of "shock". Overnight the pool took a turn for the worse. I am now dealing with a murky green swamp. I have strted adding household bleach through the skimmer with the clorinator off and the Nature 2 removed. Am I heading in the right direction and how long do I wait before trying something else? CYA and clorine levels are near 0. PH is 7.2 and TA is about 70. Thanks in advance for any help you can offer.