Green Algae Stains At Bottom Of Pool Liners Around Sides

[pectin]

I have finally managed to get pool under control in its chemistry... and now around the sides of the pool [not all] have some greenish stains from the algae. I have put in 'Metal Free' from pool chemistry to try to remove the metals from my pool it worked well but now how do I remove the stains?? I have tried scrubbing it with a hard bristol Nylon Pool bush and it did not come out instead it made the liner patterns kinda faded or disappear... so I stopped doing it... how and what can I do... any chemicals that can remove it... The pool still is a little low on Alk. Advise... baking powder? Size is around 22,000 gallons liner pool.

[polyvue]

I have finally managed to get pool under control in its chemistry... and now around the sides of the pool [not all] have some greenish stains from the algae. I have put in 'Metal Free' from pool chemistry to try to remove the metals from my pool it worked well but now how do I remove the stains?? I have tried scrubbing it with a hard bristol Nylon Pool bush and it did not come out instead it made the liner patterns kinda faded or disappear... so I stopped doing it... how and what can I do... any chemicals that can remove it... The pool still is a little low on Alk. Advise... baking powder? Size is around 22,000 gallons liner pool.

First, confirm the type of stain. Try positioning a Trichlor (chlorine compound) tablet in the pool so that it comes into contact with the stain. If the stain lifts or fades in a short time, the stain is probably organic. With elevated levels of chlorine and frequent brushing the stains will eventually go away. If you suspect metal staining, apply a vitamin C tablet to the affected area. If the vitamin C works, treat for metal stains (below).

For metal stains, consider applying an ascorbic acid treatment --- if the stains cover a wide area, you can perform this procedure pool-wide; or just apply topically for smaller areas. See Stain removal via ascorbic acid treatment for details. Be aware that the process requires reducing chlorine down so that it can no longer be measured. As far as I know, there are only a couple of ways to permanently remove metals (to prevent restaining) from the pool water. A.) Drain / vacuum to waste / backwash to remove the water; or B.) Hire a company that performs reverse osmosis filtering to remove them. (Distillation would work, too, but I've never heard of that being tried for the volume of water typical in a pool.) Refill with water known to be metal-free and subsequently never add copper-based algaecides or minerals disbursed via algae-control systems (Nature 2) etc.

[canthony]

I thought I'd comment on this since I just finished dealing with the exact same situation. My pool got out of control - lots of green algae, tons of shocking and treatments needed. Once all the algae was dead, I found that there were still brown/black/dark green stains along my walls where the worst of the algae had been. These stains simply would not come off with regular scrubbing and shocking.

After finding this site, I realized that I had not been shocking using the appropriate amounts of chlorine. I followed the guidelines here and went to poolcalculator.com. Based on it's suggestions, I added chlorine up the mustard algae shock level (I also had mustard algae). Not only did this greatly improve my overall pool conditions, all of the stains disappeared immediately, after having been there for months. Keep in mind, depending on your CYA levels, this may require a much greater amount of chlorine than you are used to; possibly something like 10 gallons of 6% bleach (recommended) or 10 lbs of cal-hypo (not my recommendation, due to the CH increase).