If you are treating larger stains or decided to buy a liquid acid sprinkle the acid evenly around the pool.
Citric acid wash for pools.
An acid wash would likely remove it you can test by lowering the water level down below the first step and pouring a 50 50 acid water mixture from a flower watering can over the step scrubbing briefly and hosing off within 60 seconds.
For citric acid for pools.
Bosh chemical vanish pool spa stain remover 2lbs natural safe citrus based works excellent on vinyl fiberglass and metals removes rust and other tough stains.
Pump the mixture into a bowl using a submersible pump.
Spray down the sides of the pool and make sure the entire surface is wet.
If it works an acid wash would be a good next step.
Dispose of what you pumped as the acid can kill frogs fish and plants.
Rinse out the bowl.
Mix it gently with a mixing stick if you need to.
Apply soda ash to the acid puddle scrubbing the mixture with a pool brush.
Pour water over any remaining.
A citric acid wash is most effective on a swimming pool that has been cleaned with all debris removed after it is drained.
4 1 out of 5 stars 105.
You will need to use 2 lb.
In your five gallon bucket add one gallon of acid to one gallon of water never the other way around.
Fill the can with 1 gallon of water and then add 1 gallon of citric acid always in that order.
Wet the sides of the pool.
When you get the ascorbic acid in the water you can turn on the pool pump and let the filters circulate the water for about a half hour.