removed liner black and green everywhere on sand

We just bought the house in September. The main drain had a horrible leak. So we replaced that and the skimmer but when we had the liner removed the sand was covered in black and green mold and even some moss. What is the best course of action to fix this? I hope to not have to shell an additional 2 grand for new sand and bottoming.


Mod Squad
LifeTime Supporter
Jul 11, 2012
Tallahassee, FL
I think they are saying the sand under the liner was green and black.

I am not sure what you should do about it. I would say nothing as long as the sand is compacted. IF you take any sand out and try to fill in the hole it may cause more problems once you put the liner back in.

With above ground pools it is taught to take dirt OUT instead of adding dirt to make it level. I would think it would be the same idea.

Hopefully someone else will come along and know the best way to deal with it.



LifeTime Supporter
TFP Expert
Aug 18, 2012
Elverson Pa.
Welcome to TFP !
Just thinking maybe you could use a pump sprayer with a water bleach solution and spray the areas to kill it off.
Could you post a picture if it ?
Also if you could add all your pool and equipment info to your sig that will help us better help you. 😎
Thanks for all the quick reply :) I used a pump sprayer and some concrobium but that's for indoor use I don't want it to be for nothing :(

It is the top layer of sand. When the pool liner was removed you can see the clean layer in some locatuons. Also it looks like where they patched it previously is clean.

Here is a photo

I don't know what a pb is. Yea we have replaced the main drain and the skimmer and both lines. The big issue is we need to build a retaining wall. We have a sloped lot on a down grade towards house.

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Only thing with bleach is I heard it only fixes for a week and it comes back I'm looking for something permanent
Pool builder wants me to try the mold control stuff he said removing and refilling would be 2k we are tapped out now as we've just bought the house in September and we just dropped 4k on the new liner maindrain and skimmer+ line
I was hoping someone might have experienced this before and knew a way to kill it all in a week so we can install new liner before the highs dip below 50 in north georgia


Mod Squad
LifeTime Supporter
Platinum Supporter
TFP Expert
In The Industry
Apr 1, 2007
Sebring, Florida
Unfortunately, I can think of no quick, easy fix for a condition that badly neglected (years!).

If you want it done in a week, I think you will have to pay someone.

If you want to clean it up yourselves, it will take much longer to scrape away all the solid debris and THEN use chlorine on it.
Only thing with bleach is I heard it only fixes for a week and it comes back I'm looking for something permanent
I am not sure why someone would say that. Bleach is the BEST way to keep organics out of your pool......on either side of your liner. Did someone propose an alternative?


Mod Squad
LifeTime Supporter
TFP Expert
Jul 10, 2009
Houston, Texas
Once you kill the mold and mildew it will stay away if you keep the ground dry, regardless of how you kill it. I think your bigger issue is going to be controlling the ground water or surface water run off to prevent that from happening again. How do you plan on addressing the rust on the pool walls?


LifeTime Supporter
Jul 3, 2014
Peoria, IL
I would second the bleach comment, spray,spray and spray some more. I do not know of anything that will kill mold like bleach will. Go 100% bleach if need be. Just wear a respirator.

And for the rust on the walls I would recommend some type of product that stops the growth of rust. There used to be a spray on or brush on type of "jelly" that we used to use in the auto body industry to neutralize the rust and prevent spreading. Then spray with silver rustoleum paint.

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LifeTime Supporter
TFP Expert
Apr 27, 2012
Grand Rapids, MI
Bleach will be cheapest, but does not last against black mold. But there is a product used on molded wood/water damaged areas called boracare that has boric acid, which penetrates wood and deeply prevents the return of mold. I have no idea if it would work on sand or not (its very thick/viscous) and sinks in to prevent a have to use a paint mixer to stir it. But it might we worth experimenting.

I've used it on a 2,000 ft crawlspace with great outcome but its pricy for that kind of coverage ($100 a jug). If you want to read up on it, check it out here:

If it sunk into the sand far enough, I might at least hold til you got the liner in.


Well-known member
Sep 15, 2013
This is a question coming out of ignorance... but, what danger does all this organic material pose under a liner? Would its continued growth/existence harm the new liner in some way? I agree it's ugly; just wondering what the practical hazard is.

How bad is the rust on the metal panels -- i.e. how deep does the rust damage go in the worst areas?
Sorry my email stopped updating me on responses some reason. The pool builder was nice enough to let us make monthly payments. The pool has been scraped free of mold I'm unsure if they added a treatment of anything on the ground. About the rust. He sanded it then applied rustoleum paint I think. All in all looks like 2800. For the bottom. They will be applying foam to the wall which is something else the previous owner neglected. The main drain was a single drain and was connected with threaded ends and Teflon tape. The guy could wiggle up and down large amounts on the maindrain plumbing so I figure that's how the ground was kept saturated for that mold

Anyways this is what it looks like now