Newbie - Stain removal via ascorbic acid

[herb396]

I have a 25K gal plaster pool which was painted 2 summers ago. In doing our opening this became victim to a stain which is covering about 85% of the surface,,it's darker in the shallow areas and on steps.

So after finding this site I ordered 5lbs of the ascorbic acid and just completed the treatment application that Marie (mbar) was kind enough to type out. Problem is that it produced very little results. The only thing that cleared up was my top step. I followed the instructions my lowering my chlorine to zero (had it tested at the local pool store) and set the filter to By Pass to Pool, waited thru the process (waiting to be amazed) and even ended up using the entire 5lbs. Two hours later, little to no improvement. I spot tested an area using a sock with the ascorbic acid and it did wipe clean.

Help!

My current readings are:
Saturation Index: 0
TDS: 700
CYA: 100
Tot Chlorine: 0
Free Chlorine: 0
pH: 7.4
Tot. Alk: 150
Adj. Total Alk: 120
Tot. Hardness: 244
Copper: 0.5

[aylad]

Hi, and welcome to the forum!

Just wanted to let you know that I asked Ben (Pooldoc) to come by and take a look at your thread to see if he could help you out, since stain removal is not in my area of knowledge.

Also wanted to let you know that when you post a thread, it goes into a queue of posts to be approved by either one of the moderators or Ben. That's why when you posted this thread the first time, you didn't see it--it took me a few minutes to get it modded in--so when you reposted the same thread, it came into the queue as a duplicate. I have deleted the duplicate thread that you posted, so that all the responders to your question can keep their information about this question in this one thread. In the future, if you post something and then don't see it appear immediately, it just means one of us has to mod it in first. It may not be immediate, but we'll get it in the forum as quickly as we can, so try not to duplicate it. There are 4 mods, plus Ben--and between us all, somebody's around the forum almost all the time.

Janet

[PoolDoc]

Hi Herb;

Just to add to what Janet said, for subscribers, your posts appear instantly, once you've posted 6x successfully.

And, now on to the stains. Before I try to give answers, I need to get some myself:

If I understand you correctly, you have a plaster pool that was unstained till this spring? And the stains appeared when you were opening the pool?

Did the stains appear as soon as you could see the sides? (That is, did they develop over the winter) Or, did you start off clear and unstained, and have the stains appear AFTER you could see the sides and bottom of the pool?

What color are the stains?

Are you on city water or well water?

Is your pool filled with the same water that fills your toilets? If yes, what color is the interior of your toilet tank?

Looking at your test results, do you know why you had a positive result for copper? Have you added copper algaecide or used a 'mineral' product or operated a ionizer or used a Nature2 unit?

Have you used a silver algaecide?

Do you have a heater? If yes, what kind?

What condition was your pool water in when you opened?

How many gallons are in your pool . . . or what size is it?

What sort of filter do you have?

What chemicals did you use at opening? What chemicals have you used since?


. . . that should be enough, for now.

By the way, I'm going to be tied up this weekend, and so is Marie I think. So if you can post before 10 pm tonight, I'll try to respond. Otherwise, you may have to wait till Tuesday.

Ben
"PoolDoc"

[herb396]

If I understand you correctly, you have a plaster pool that was unstained till this spring? And the stains appeared when you were opening the pool? - We have had minor stains in the past,,but two years ago we had new coping and tile put on,,so pool was drained acid washed and painted...filled with well water. Last year there was no staining issues.

Did the stains appear as soon as you could see the sides? (That is, did they develop over the winter) Or, did you start off clear and unstained, and have the stains appear AFTER you could see the sides and bottom of the pool? The process started off clear and developed as the water was clearing up

What color are the stains? light brown

Are you on city water or well water? well

Is your pool filled with the same water that fills your toilets? If yes, what color is the interior of your toilet tank? Yes and we do have some residual staining in the toilet tanks, especially if the softer is low on salt.

Looking at your test results, do you know why you had a positive result for copper? Have you added copper algaecide or used a 'mineral' product or operated a ionizer or used a Nature2 unit? - No guess on the copper,,that reading seems to go away at different times,,we did hit it with a heavy does of algaecide thinking the stain was algae put with hTh brand.

Have you used a silver algaecide? We used the hTh brand from Wal-Mart

Do you have a heater? If yes, what kind? - Yes we do have a gas heater but I cut the line and by passed about a month ago to try and rule this out.

What condition was your pool water in when you opened? - Water was clear and pool was dirty,kind of green ,,we have a mesh cover but a lot of oak trees surround it,,so we set a lot of sediments from leaves and debri.

How many gallons are in your pool . . . or what size is it? - approx 25,ooo gals

What sort of filter do you have? - We have a sand filter,,just cleaned out last week and put in new Zeobrite

What chemicals did you use at opening? What chemicals have you used since? - Our opening began with vacuumed to waste and running the pump 24/7 for the first three weeks (starting in late May), pool wasn't really clearing up so we began using then generic tablets in the skimmer,,,pool stayed green very light improvement,,,tested at local store, typical raise pH and Alk so we added the generic stuff as directed,,was told our free chlorine was zero many times over several weeks,,,I then I dumped about 10 gals of liquid chlorine in,,still didn't seen to hold any chlorine, was told to start using the BioGaurd shock and put 10 scopes in a day,water then started to be more cloudy/white,,,,stains could then be seen more. Thats when we blasted wit with algaecide (about two bottles) stain did seen to lift a little) ,,chlorine levels then became stable,,I then put a bottle of crystal blue in,,water slightly cleared up. Water was now testing good balance ,,had a pool party with kids, water was splashed around all day (there was some foaming),,but for a full week the water is crystal clear.

Lots of info I know,,but feel very lost at the moment. Thank you

[PoolDoc]

Ok.

Most likely, you have iron in your well water. Many people don't realize that water softeners remove iron. If you filled with water that had passed through the softener, the iron would have been removed . . . UNTIL the zeolite in the softener was saturated with iron. With most wells, the water needed to refill with the pool would have saturated your zeolite (not Zeobrite) several times over.

In the past, you may not have had problems because you didn't use enough water to 'break through' your softener. But, once you had to the fill the pool, watch out!

(Of course, if you have never used softened water to fill your pool, you can forget all this, except as a reference for the future.)

One other issue: it's quite an irony, but the most common way to REMOVE stains, acid washing, ends up making pool surfaces much MORE susceptible to staining. Acid washing works by corroding away the top layer of plaster, exposing a new white -- but rough and porous -- surface.

Unfortunately, iron stains that have been in place for awhile don't always come up that easily.

Here's your best bet:

0. Start running your pump 24/7.

1. Carefully lower your pH to 6.4 - 6.8. If your kit only goes to 6.8, carefully lower it to that, and then add a little more acid. Keep it there for several weeks. (In essence, you are doing a very, very mild acid wash, among other things.)

2. Use twice weekly doses of polyquat 60 to allow you to run low levels of chlorine without getting a pool full of algae.

3. Maintain low chlorine levels between 0.5 and 2 ppm.

4. Add 1 1/2 times the maximum dose on Metal Magnet or a similar liquid metal control agent. Be sure to allow for any prior use in the past 2 weeks: deduct that from what you add.

5. Brush the pool a lot, especially starting a day after you get the chems in line.


If you're lucky, this will remove the stains gradually. If they do, remember that you are NOT done. You will have moved the iron OFF your pool walls, but BACK into your pool water. You've still got get the iron OUT of your pool, and ONTO your filter.

Chlorinate by putting trichlor tabs in the skimmer. Doing so will help lower the pH and will tend to bring the iron out on the filter. Backwash as needed. If the backwash is orange-brown from the iron, you are making progress.

After two weeks, you're pretty much done: if the iron is not off by then, you'll have to think about replastering, painting, acid washing again, or just living with it.

You can also remove the iron by concentrated application of "Iron Out" which is available from the company in 50# pails. This requires a drained pool, too. BTW, do NOT use Iron Out if you have asthma, and DO have someone around to 'rescue' you if there's a problem. Sodium hydrosulfite (present in Iron Out) fumes can trigger SEVERE acute asthmatic attacks.

Regardless, start bringing your pH up SLOWLY, using borax. Once you get up to 7.6 or so, remove ALL trichlor from your system. (Really! Make sure that there is absolutely NONE anywhere in your pool, pipes or feeder!) Then begin chlorinating using calcium hypochlorite granular chlorine, added DIRECTLY to the skimmer in small doses. Buy some from Leslie's if you need to do so.

Gradually raise the chlorine to around 20 ppm (given your CYA of 100+) and hold it there for at least a week.

Once you've done so, all or most of the iron in your pool water will be gone. And, you'll have removed stains you're likely to remove without draining.

Good luck,

Ben

[herb396]

Ben,
I appreciate the guidance, feels like I've been at a total loss with no plan. I have a few questions:

1. Carefully lower your pH to 6.4 - 6.8. (what do I do to lower the pH?) then add a little more acid (meaning the same ascorbic acid ?) (how much is a little?) Keep it there for several weeks. In essence, you are doing a very, very mild acid wash, among other things.

2. Use twice weekly doses of polyquat 60 to allow you to run low levels of chlorine without getting a pool full of algae. (understood)

3. Maintain low chlorine levels between 0.5 and 2 ppm. (is the pool swimmable during this time?)

4. Add 1 1/2 times the maximum dose on Metal Magnet or a similar liquid metal control agent. Be sure to allow for any prior use in the past 2 weeks: deduct that from what you add. (would Pool Stain Treat by United Chemicals be an equivalent?)

5. Brush the pool a lot, especially starting a day after you get the chems in line. (understood)


Chlorinate by putting trichlor tabs (never heard of these, where can I get them?)

Thanks for the help !