The yellow stains are most likely algae. Superchlorinate and lots of brushing until it is gone. Then brush again. You may want to clean the filter too.
Use a steal wire brush to brush off the yellow stains. Also, it might help to keep the chlorine level high.
Bleach might do it.
Also investigate the cause of the stains by observing pool users.
Let all the water out. Use any type of baking soda and scrub the walls. Then, remove the baking soda by washing down the walls with water.
Stain Magnet from GLB.
Drain pool and clean with muriatic acid
My experience is that the stains will go away by themselves, through the effects of the chlorination of the water. Does not matter if the pool is a salt pool or fresh water pool. If the pool has a plaster finish, brushing the stains with a wire pool brush will speed up the process.
First, find out what the stains are. Iron staining? Stain from using Morton System Saver salt pellets? Algae? Your pool service man should be able to tell you. Then take the appropriate action to remove - ask your local pool shop or pool service person.
yu lift it up
What is the best way to remove algae stains from the pool liner?Empty the pool, use a soft brush, mild detergent and water to remove algae stains from the pool liner. Thoroughly rinse and dry before refilling or storage. http://www.air-inflatablepools.com
Use a 10% solution of pool acid and wash with water
Scrub it down with fresh water and a stiff broom or brush
You do not get stains from overchlorination of pool water. Look to another source like pH too high or too low, high copper levels, high mineral levels like iron etc. Depends too on what type of stains
Use a natural ascorbic acid based pool product to clean stains on walls in the pool. Once applied, this product almost immediately removes most stains. Most pool stains come from metals in the water. Test your fill water to make sure it doesn't contain high concentrations of metals, if you fill your pool from sources other than city water.
Since you cannot remove the "stains" with the methods you have tried perhaps the stains are from too much acid or high acid levels. Are there also copper colored stains as well? Do you have a pool heater in the system? If so, then it is copper stains from an acidic pool water. The over acid conditions are stripping the copper from the heater copper tubing. k
The stain in pool liners look unsightly and ruin the appearance of your pool. You can Remove the Pool Stains with the Brush, if the stains caused by metallic reactions then you can either use chlorine tablets or a commercial metal stain remover.
Sounds like the PH is wrong in the pool try adjusting to the correct PH