Proper Method Of Chemical Addition To A Vinyl Liner

by Sapphira
(Rockport TX)

Is there special care to be taken when adding chemicals (Muriatic Acid or Soda Ash, etc) to and in-ground pool having a vinyl liner?

Thanks for the question Sapphira

Yes, you should take some extra precautions when adding some chemicals to a pool with a vinyl liner. Muriatic acid and chlorine are the main chemicals. Acid is heavier than water and will sink straight to the bottom.

When adding acid, it's best to mix it first in a bucket with water. This dilutes it a bit. Always add acid to water, never water to acid.

Sweep the bottom and sides of the pool to break up any hot spots. The same technique should be used for chlorine. Soda ash or sodium bicarb. can be directly put into the pool because it's not as caustic. But, you can make it a habit of using a bucket and making a slurry of the chemicals.

The only exception is calcium chloride. You should add that directly into the pool and sweep the sides and steps. If you mix calcium and water, it may "steam" up and burn you. This happened to me at the YMCA. I had a pool route in Arizona where the hardness of the water can exceed 300ppm. There was never any need to add calcium.

Here in Oregon the water is very soft, about 2ppm, so adding calcium to a plaster pool is necessary. I didn't know to not mix calcium with water, so I did, and learned that doing so gave me 1st and 2nd degree burns on my hands.
Tough way to learn, but I never did that again.

If you add acid or chlorine straight into the pool it might stain or burn the liner. Using the above techniques will help keep your liner looking good for years to come.

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.

Swimming Pool Questions and Answers

Check back to this post for answers. Hope this helps and have a great Summer.


Click here to read or post comments

Return to Vinyl Swimming Pool Liners.

Chemical Burns

by Marlene Danko
(Toledo, OH )

We had a brand new liner last year and closed the pool the same way we have for the last 14 years. This year when we opened it we have huge white spots on the bottom and were told they are chemical burns.

We live in Toledo Ohio and had a very harsh winter. We heard the water froze but not the chemicals.

We used the same thing as in the past. Can you explain what happened

Thank You


I could take pictures if you would like.

Thanks for the question Marlene

With such little to go on it's difficult to say with any degree of certainty or accuracy what may have happened.

What kind of chemicals did you use? Granular or liquid chlorine? Dichlor chlorine? Did you dissolve it in a bucket then broadcast it around the perimeter of the pool and sweep or just add it to the pool? Did you use acid and not sweep? Acid is heavier than water and will always sink to the bottom. Were there any chlorine tabs left on the bottom?

It's possible for pre-dissolved shock to cause stains and bleaching of a liner. I would suspect this to happen if the shock was added while the pump was off.

What may have happened is some kind of organic matter was growing and producing a natural substance that ate your liner away. Your liner warranty may say something to the effect that the liner must be kept clean and water balanced at all times.

Jack’s Magic Stain ID kit can help determine the kind of stain and the steps you can take.

I hope this has answered your question to your satisfaction.

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.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.

Have a great Summer.


Click here to post comments

Return to Vinyl Swimming Pool Liners.

Chlorine Stain On Above Ground Pool With Vinyl Liner

by Treed
(Edgewater, MD USA)

I have an above ground pool with a vinyl liner.

My husband closed the pool last season and threw a couple of chlorine tablets in the pool to keep the algae down.

I just found out he did this when we started the opening process this season.

There are bleached spots where the tablets laid all winter. The liner looks like it lost its elasticity (sp?) from the tablets laying on the liner during the winter months.

Should I patch those spots?

There does not to appear to be any holes, however, I don't want to fill the pool and find out otherwise, flooding my neighbors yard with 12,000 gallons of water.

Any information you can provide is greatly appreciated.


Thanks for the question Treed

It's really a little difficult to say, to any degree of certainty, of what may or may not happen.

If it's just for a few days, even a few weeks that the chlorine tab sat on the bottom, I would probably say no need to worry.

Many liners can withstand a chlorine stain from a tab that laid there for a certain amount of time.

Vinyl liners are pretty touch and can take alot of punishment before they give up.

But an entire Winter could be something else.

The water would be very cold so the chlorine tab would dissolve very slowly, thus making longer contact with the liner.

If I were you, I'd call in a vinyl liner professional that you can trust and explain the situation to him.

I think this is a case where someone would actually need to look at the liner. Most of the time a simple email or answer to a question would suffice, but in this case you might want to call someone in.

Hopefully you can get away with a patch, but that depends on the outer edges of the stain and how good the patch will hold up.

If you have any additional questions or would like to comment on your post, you can find it on the Q&A page in the "Pool Liner" category:

Swimming Pool Questions and Answers

Hope this helps and good luck with your pool.


Click here to read or post comments

Return to Vinyl Swimming Pool Liners.

Acidity In The Swimming Pool Water..Too Acidic

by Nee
(Lynbrook, New York)

My water was tested and they told me the water has too much acid in it. I now find my liner is getting rust spots on it.

What do I do to lower the acid in the water and how do I get rid of the rust spots on the liner?

Is this unhealthy to swim in?

Thanks for your question Nee

You talking about the pH level of your swimming pool. The pH level ranges from 0 - 14...7 being neutral. Anything 6.9 and under is considered acidic and anything over 7.1 is alkaline.

If your pool water is acidic it will show a low pH level and/or total alkalinity level.

I would suggest getting a Taylor Reagent FAS-DPD K-2006 pool water test kit. It's the one most pool professionals use and the most accurate.

Water Testing Kit..FAQ..Chemistry Testing..Procedures..Balance..Swimming..

You'll probably need to raise both your pH and total alkalinity levels. Here are the links and charts to do that quickly and easily.

Swimming Pool Alkalinity..How To Adjust Your Pool Chemistry & Water Balance

Swimming Pool pH Levels..Chemistry..Alkalinity..Water..Care

Concerning the rust spots on the liner...

If you only have a couple of spots, you can use a sock with commercial Vitamin C tablets in it. Drop the sock on a spot for about 2 - 3 minutes and the stain should start to fade. If the rust stains/spots don't go away after half an hour, try another few minutes with the sock filled with Vitamin C.

If this doesn't work, you might need to go to an asorbic acid treatment. Here's how to do that:

Bring your chlorine down to as close to 0.0 as you can. The chlorine will use use the asorbic acid so you'll need to get the chlorine down as far as it can go.

You can add Polyquat 60 algaecide to avoid getting pool algae while the chlorine is that low.

You'll use about 1/2 to 1lb.of ascorbic acid per 10,000 gal. Try to go on the lighter side to see if the stains come off before adding any more.

With the filter on circulate, pour the asorbic acid around the perimeter of the pool. Allow the water to circulate for 1/2 hour.

Depending on just how extensive the iron stains are, you might need to start using a sequestrant for metals.

If the stains are gone gone with this treatment, keep the filter in circulate mode and add more ascorbic acid where the stains are.

Leave the filter in circulate until all the stains are gone. Add more asorbic acid if needed.

When all of the stains and spots are gone, you can add the sequestering agent for the number of gallons of your pool.

Put the pool filter back on the "FILTER" setting and leave it on 24/7.

This might lower your pH but you can use the above link to adjust that.

Just remember that you'll have the asorbic acid in the pool so when you add the chlorine the acid will soak it up first, then your water. You'll probably go through alot of pool chlorine to re-balance out your pool.

Once the chlorine starts to even out, stabilize, and hold, that means there should not be any more asorbic acid in the pool. Be sure to have the cyanuric acid level in check as well.

Adjust Your Swimming Pool Chlorine..Chemistry..Salt Water Maintenance..Inground

Try to keep you pH level low, around 7.2ppm for time being, then adjust it slowly. And don't shock the pool for at least 2 weeks.

This addresses the issue of rust spots, but not the reason. You might have some metal rust coming through the liner. As the above is a bandage to the problem, you may want to find the real issue and take care of that.

Hope this helps and have a great Summer


Click here to read or post comments

Return to Vinyl Swimming Pool Liners.

swimming pool care, basic pool care, above ground pool maintenance, inground, salt water

Click Here To Learn How This eBook Can Save You TONS Of Time & Money

Click Here To Learn The Best Way To Clear Up Your Pool 

Recent Articles

  1. White Slimy Film On The Bottom Of Pool

    the water was crystal clear but upon skimming the top we noticed a white slimy film completely covering the pool liner.

    Read More

  2. High Cynaric Acid

    My pool is a 26,000 gallon above ground vinyl liner. around 7/31/2014 the cya raised to 113

    Read More

  3. Can Super Floc Remove Pool Algae?

    Will raising the pH level and adding Superfloc get rid of algae?

    Read More