If you post all of your chemistry, it will be easier to help you. Also post where you fill water came from (well, city water) and if you know if you have any metal in your water. Post:
Free Chlorine
Combined Chlorine
Total Chlorine
Ph
Alkalinity
Calcium
Cya (stabalizer)
size, (gallons) of pool, filter, and you have a plaster pool.

Thanks, we can help you better if we can see what is going on with the water.