Quote Originally Posted by ekjan View Post
So..what causes a stained liner?
Usually, metals. Most often either IRON from well water or old rusty distribution mains, or COPPER from ionizers, algaecides, or corroding pool heaters. Occasionally, organic material such as oak or hickory leaves will leave stains.

What gets rid of stains?
For metal stains: http://www.poolforum.com/pf2/showthread.php?7923

Will brushing the pool get rid of the stains?
Can help prevent them; usually won't remove them.

If the chemicals stay out of balance will the liner stay stained?
Water 'balance' (pH + TA + CH) is not closely related to stains. Low or high pH is.

The entire pool is the same yellow/green color, no difference anywhere.
Vitamin C test will tell if it's a stained liner, or yellow water.

If the chlorine stays in the 5-10 range isn't that too strong to swim in for children?
No. Dermatologists TREAT children for a variety of skin conditions with 'bleach baths' of 50 - 100 ppm free chlorine with ZERO stabilizer.

What will I do differently when the kit arrives?
Test the pool, and tell us what you find. You can prepare by watching these videos: http://www.poolforum.com/pf2/showthread.php?17157