Pool was opened 7 days ago. due to a warm and wet winter it was black on opening. 7 days later and lots of work the water is pretty but the steps have a brown/tan maybe a little yellow stain or growth on them. There are a few places on the floor and wall of pool also that are tan to yellow looking that I can not get rid of. They will not brush off. Wednesday evening at 8pm using the pool calculator I put in enough bleach to raise the chlorine to 24. Due to work I was not able to test pool again until Fri at 4pm. Chlorine reads .5 with no change in markings on steps but some of the wall may be slightly better. Still will not brush away. Is this Algea or a stain? If it was just a stain wouldn't I still have some chlorine left less than 48 hours after raising it that high? No rain since last shocking and temps in upper 80's. I have been adding 5-6 182oz jugs of bleach every evening since opening. Seems like I've used a lot of bleach to still have markings left. Do I continue on this same path or do I need to try something else? Any help would be appreciated? Pool is gunite approx 25560 gallons and cartridge filters that have required cleaning 4 times since opening. My ph is 7.6 and TA is 100. Calcium hardness was 240. Pool store said my cya was 60 although when I tested it a few days (right after opening) before the store did I got a reading of less than 30. Also I have been able to keep 5ppm over night but not 24hrs. 5ppm is as high as my test kit reads. How long should I strive to keep chlorine at or above 5ppm?