thanks for the info. on removing stains with ascorbic acid. it worked well. seven and ahalf pounds (80,000 gal. pool) removed all stains from vinyl liner, pump baskets, all plastics are back to original white colors, and i am sure that the insides of my sand fillters are clean as well. pool went from a green color to a nice blue color (pos. copper issue) as metals were released back into the water. i used sequestering agents as instructed. the pool went very cloudy (milky look) and my TDS readings were 5000 plus (normaly around 1500). i removed about 55 to 60,000 gal. of water to pool and is still showing cloudy and blue, but TDS is down to 3000. incoming water is at 150 to170 total alk. and pH is at a7.80 to 8.00. calcium hardness is at 360. i use bromine and shock with potassium monopersulfate (both are acidic with low to no calcium i think). so now the pool has about 60,000 gal. of fresh water, bromine at 4ppm and a cloudy pool but still blue. so i decided to shock with monopersulfate and use some clairifier. came back the next day and the pool is green and all the staining has come back on the liner. it is amazing on how the staining and water color changed over night. i am going to redrain the entire pool, clean the vinyl liner with an ascorbic acid-water mix, which i know will take the stain off, flush the metals down the drain and refill the pool. i guess i probably made some mistakes on this stain removal project. again, i think this process is great and i will be using it in the future. staining is a big problem with this pool and out of all the processes i have tried, this is the best. there is no better process that i have found for this perticular pool. if anyone has any info that could help clear up any issues that i had or any useful tips in general regarding this i would sure love to here it...thanks for your time....poolteh..