I recently noticed brown stains on my vents. Tested with vitamin c tablets and it cleared the stains. I have been placing socks over the vents to get rid of iron but this seems to be very slow paced. My water is crystal clear. I also have been struggling with my pH balance. Can't semester to get it above 6.4. Could the iron keep pH out of balance? I have an in ground pool 26000 gallons with vinyl lining. Thanks for your help!