https://www.answers.com/water-sports/Why_does_my_Intex_salt_water_pool_system_keep_turning_the_water_brown_-_goes_into_the_system_clear_but_water_exits_the_system_-_and_into_pool_-_brownish
Are you using iodized salt or pool salt? I've read that the iodine in the iodized salt will leave yellow staining in the pool.
salt water poolintexsystemkeepturning
https://www.answers.com/water-sports/Does_Limestone_rock_affect_your_salt_water_pool_Ph_levels_and_does_the_rocks_breakdown_from_the_salt
I just conducted an experiment with a small amount of limstone in beakers of acids and bases and the Ph levels stayed the same.
salt water poollimestonerockaffectph