low/no chlorine and staining

[KimS]

Since I began using the chlorine sticks that only dissolve when the pump is on, I have had numerous water tests that indicate I have NO or very little chlorine in the water. I follow the pool sotre instructions, (shock the pool etc.) but still get the same results. I now have a 'film' of a stain on the side walls of the deep end of the pool. (I am assuming this cannot be a marcite stain/issue since we just had the pool resurfaced 2 years ago.)

Could the stain in the deep end (color of mustard algea but I know it's not algea) be caused by low chlorine? Does anyone know what I can do to get rid of the stain? Or, does anyone know what I can do to maintain the proper level of chlorine?

[Dan101]

The stick chlorine you use probably has a pH of under 3, and may be lowering the pH of the pool water. Low pH or low total alkalinity can result in corrosive water and staining of the pool's surfaces. http://www.havuz.org/pool-problems/pool-staining.htm

If the chlorine level is consistently low you should check the level of conditioner (cyanuric acid) in the pool. Low conditioner levels results in the chlorine evaporating in sunlight. You could also consider regular dosing by hand rather than relying on the dissolving of the sticks when the filter is running.

If the conditioner is OK, the reason for the high chlorine demand should be investigated. I have been using the Pool Wizard for about 18 months and find I use hardly any chlorine nowadays. My pool is marcite and I used to have nightmares with algae every summer. I used to shock twice a week and still had some algae growth appearing. Now I almost never shock and add just a hanful of chlorine twice a week. What a pleasure!