Stains in the deep in of my pool

[pperkins1027]

Hello. I am a new pool owner. I recently moved to a house that has a 20000 gallon in ground concrete pool. The previous owners left it a complete mess. There was very little water in it. But what was left was a horrible leafy stinky green puddle in the deep end. After many hours of work. We drained what was left and completely scrubbed the entire pool. Thank goodness everything is still in working order. After refilling and balancing and countless hours we are able to use the pool and the water is crystal clear.
However there is still a huge stain from where the leaves branches and debris set in the little bit of water that was left. A friend who has a pool told us that after a while the stains would disappear. They still have not. Was wonder if this is correct or if there is anything we can use to get rid of the stains

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[chem geek]

Welcome to TFP!

Since the stains are organic, chlorine will fade them, but it may take months. If you don't want to wait you can elevate your chlorine level to make it go faster and also change your circulation pattern to ensure that there is water flow to the deep end of the pool where the stains are located. An elevated chlorine level that will speed things up by roughly a factor of 2 would be an FC/CYA ratio of around 15%, assuming you are following our guidelines for Free Chlorine (FC) and Cyanuric Acid (CYA) management. If you want to go faster than that, you can go up to SLAM levels which will accelerate things by a factor of 10, but of course all of this acceleration also wears more on everything though with a concrete pool there's not much to wear (compared to a vinyl pool with medium blue color using organic dyes).

If the stains are in a small localized area, you can use a Trichlor puck on the stain but realize this can leave a white mark on the plaster so you'd want to move the puck around to soften any edges so you won't see them. Do not leave the puck on any longer than necessary for fading the stain since the acidity of the Trichlor will degrade the plaster in the area (dissolves calcium carbonate). For a larger area, the elevated chlorine approach would be better and less harmful to the plaster.

 

[pperkins1027]

Great. Thanks. I will try to SLAM the pool.

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