Ring Around The Vinyl Liner At The Water Line

by Melissa

We converted our above ground pool to saltwater two years ago. Every year when we uncover the pool, we have a black ring around where the water was and evaporated.

What would be the best thing to scrub this black ring with? Can I use baking soda or non-iodized salt with a mitt?

Will the fresh water cleaners also be OK to use in the salt pool? The pool PH and chlorine are balanced. We installed an Aquatrol and have been very happy with it.

Thanks, Melissa

Thanks for the question Melissa

This definitely sounds like an oganic stain. The best way to get rid of an organic stain is to shock the pool. It also helps to apply a 2:1 mixture of bleach and water to the affected area and lightly scrub with a soft bristle brush. Put the mixture into a spray bottle and spray an affected area. Allow to sit for a few seconds then scrub. Baking soda is also a good substitute. You can also try vinegar. It's a bit less caustic and has less fumes.

Lo-Chlor Multi Stain Remover is another choice, Follow the directions on the bottle. The main ingredients for that are Sulfamic acid, Oxalic acid, and Polybasic organic acid.

Shocking is a process, not an event. The trick is to get AND keep the chlorine above 10 - 12ppm for a period of time. You'll need to manually dose the pool with chlorine to keep it at 10 - 12ppm. Make the adjustment at night, then retest in the morning. Be sure to have the pump running 24/7. remember to get the pH down to 7.0 - 7.2. Chlorine is more active at a slightly lower pH.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great Summer.


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Descaling Of Inground Pool Liner

by Tammy
(Newburgh, IN)

The pH has been super high from day 1. Salt generator system.

Have white scaling all over the pool liner (bottom and sides). Have finally gotten pH below 7.0 and alk down to about 120.

Put a phosphate free descaler in with no results.

Want to use muriatic acid but don't know how much to use.


Thanks for the question Tammy

I'd like to have your complete chemical readings:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper).

It makes troubleshooting much easier. You have scaling for a reason. We need to find out the reason or you might find yourself in this situation again.

Next, I would advise you to not use muriatic acid on a vinyl liner. Normally for scaling, you want to dilute the acid to a 4:1 ratio with water, but even this ratio might be too acidic for a vinyl liner. You run the risk of a chemical bleach out or burn.

There are alternatives to using acid to remove scaling from a liner. GLB has many good products. Pool Basics Tile & Vinyl Liner Cleaner is also pretty good.

If you want to go a more natural route, you can get a soft bristle brush and a spray bottle and fill it with raw apple cider vinegar. Brush the affected area first, then spray on the vinegar. Allow to sit for 4 - 5 minutes, then brush off. The walls of the pool will require more attention because the spray will drip to the bottom.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Pool Liner" category and the bottom of the Inground Swimming Pool Liners page.

Check back to this post for updates or answers.

If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of your choice and I'll answer your questions by phone.

Contact Me


Hope this helps and have a great Summer.


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Soft Spots In Vinyl Pool Liner

by Melany
(Winfield, Alabama)

What Would Cause Soft Spots In Vinyl Pool Liner?

I had an inground concrete pool with vinyl liner installed last September.

We got in the pool yesterday for the first time this season and found a couple of soft spots (places that felt "mushy").

These spots were out in the pool near a seam.

Any ideas?

And how do you fix this problem?

Thanks for the question Melany

What I've found is when a newly installed vinyl liner becomes "mushy", especially around the seams, it normally means there's a hole or leak.

I've not personally done the following, but a couple of other pool guys who I knew in Arizona did this, and they said it worked. I mostly worked on inground pools. Some with vinyl liners.

Get a bottle of red food coloring (any dark color works) and swim to the mushy or suspicious place in the pool. Put 2 - 3 drops right near the area. If the food coloring goes into the seam or hole, that means you have a leak. You may have to do this a few times.

Many leaks happen on or around the seams.

The water is getting underneath the liner and causing a pocket of water.

You may want to check out this post:

Inground Pool Steel Walls..Should You Use Foam On The Walls?

If the liner is only a year old, I would call the:


Business you purchased it from


It's probably still under warranty. They should fix it. Hopefully you still have your receipt or some kind of copy of the purchase.

Hope this helps and have a wonderful swimming season.


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Sticky Pool Algaecide On Vinyl Liner

by Jeff
(Columbus, GA)

How Do I Get Sticky Substance Out Of Pool After Using Algaecide?

I added some algaecide to my pool and as soon as it hit the water it turned into a sticky gel. I then used my brush and it attached itself to the brush and will not come clean.

Now the liner is sticky and grainy.


1. Why did this happen? Does algaecide "expire"?

2. How can I remove this substance?

Thank you for your help.

Thanks for the question Jeff

Not too often I get a question that I really need to think about. I kept saying to myself, "Where did I hear this?"

Then it hit me. It happened only once when I was doing pools in Arizona. I took over a couple of pools from another pool guy who was fired. He put some algaecide in the pool and the same thing happened.

I think this is your problem.

You might have what is known as "pool goo" or "pool tar". This attaches itself to vinyl liners after a certain kind of pool algaecide is used.

Vinyl manufacturers use a substance called "plasticisers". They keep the vinyl flexible and stable. They get kicked up during sweeping/opening of the pool. This normally happens the 1st or 2nd opening of the pool with a new vinyl liner.

Many pool algaecides use what is called a "Quat-humate". Humates is the decomposition of organic matter such as leaves, grass, soil, etc...It sometimes happens with algaecide products like Back Up.

You can remove the quat-humate by brushing with BioGuard Surface Cleaner. This helps dissolve any oils. Allow the filtration system to get rid of it.

As the water heats up it will be easier to do this. If you have a heater I would encourage you to use it to help speed up the process.

The way I did it required a few steps:

1. You need to stop using quaternary algaecides. No algaecides with metals or copper.

2. Get your pool pH between 7.0 - 7.2 and keep it there until the problem is solved. Go back to 7.6 - 7.8ppm after that.

3. Shock the pool to 6.0 - 8.0 ppm. Use a liquid chlorine if you have hard fill water.

Swimming Pool Chlorine

Pool Shock

4. Filter 24/7. Keep an eye on the filter pressure

5. Backwash filter once per day

6. Be sure to keep the pool water level between 1/3 - 1/2 up from the skimmer. Water level that's too low will draw in air.

7. Brush and vacuum

Hope this helps and let me know how it turns out for you.


Follow Up Comment
By: Jeff
Date: April 28,2011


Thanks for the response. After looking at the bottle, this algaecide did have copper, so I'm sure this is my issue.

You mentioned using the BioGuard Surface Cleaner...can this be used "subsurface"?

My entire liner is covered with this.

I am beginning the process and will let you know how it goes.

Thanks again.

Follow Up From Robert
Date: April 28,2011

Thanks for the follow up Jeff

I believe the new name for the product is BioGuard Off The Wall Surface Cleaner. My understanding is that it's used only at the water line.

I used a similar product, but I can't think of the name at the moment. This was about 10 years ago.

You shouldn't allow this product on the surface for more than 30 minutes and it's not to be used on copper, brass, marble or galvanized surfaces.

Let me know how it turns out for you.


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Black Alage In Vinyl Pool

Within the last 3 months my pool has got the black spots all over the bottom I've scrubbed the bottom with my brush but it doesn't move I've put stuff from my pool store in and it didn't seem to help I do have a vinyl liner. if there is anything I can put in it to remove it would be great.

Hi Jim. Black algae is rare with a vinyl liner. It can happen, but it's more with plaster than vinyl. Black algae needs something to dig into and vinyl doesn't offer that. Many times it can be mold growing underneath the liner.

It would be great to have your chemical numbers: FC, pH, TA, CH, CYA, metals, filter kind, and all chemicals you've used.

Here are some good posts to look over:

Nasty Black Algae

Black Algae


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