Fighting Metal Stains - Getting Ready to Use Ascorbic Acid Tonight.....

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
I have metal stains on my pool liner. I tested with a crushed up Vitamin C tablet and confirmed what they were, now it's time to perform the ascorbic acid treatment and I just wanted to make sure I had my plan right before starting when I get home from work today. Here's where I am:

FC - 2.0
CC - 0.5
pH - 8.0
TA - 120
Ca - 190
CYA - 55
30k inground saltwater pool with vinyl liner

This morning I turned off the SWG and dumped one quart of Polyquat 60 into the pool. By the time I get home I'm sure the FC will be down close to 0. My plan is as follows:

1 - Put multiport on recirculate and turn pump on continuously (24/7)
2 - Add about 100 oz of muriatic acid to bring pH down to 7.2
3 - Wait 30 mins
4 - Apply @ 2 lbs. of ascorbic acid
5 - Wait 1 hr to see if stains disappear, repeat steps 4 & 5 until stains are gone
6 - Add sequestering agent
7 - Put multiport on filter
8 - Wait 24 hrs
9 - Rebalance water - bring pH up to 7.2 and use bleach to bring up FC to 5
10 - Turn on SWG and set to 80 (where i typically keep it)
11 - Put pump back on timer
12 - Wait 1-2 weeks
13 - Bring pH back up to 7.5
14 - Use sequestrant weekly from here on out

Sooooooo, what am I missing? Did I add enough polyquat? Should I turn my SWG back on when I said I should? Any tips or tricks?

Help is greatly appreciated....
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
Also, I think the source of the metal that's causing my staining is inside my skimmer assemblies (2). I can see definite rust stains in there and both skimmers have prominent stains around them. It seems like there is metal in there but I can't see it. Do the skimmer assemblies typically have metallic parts? If that's the source, is there anything i can do to alleviate the issue?
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
Just in case you don't have this, Ascorbic Treatment to rid Pool of metal stains

No, skimmers do not typically have metal in them and would not be a source of metals in the water unless your pool is very old. The most common sources of metal are well water, algaecide that contains copper, "mineral sanitizer" systems and copper dissolved by PH at 7.0 or lower from heaters or old plumbing.
 

basod

Gold Supporter
May 27, 2015
255
Mount Cheaha Alabama
Sounds like you have the method down pat. Why do the treatment now during swim season when the FC will have to be low and warm water temperatures? One you'll have insufficient santizer to swim and two much greater risk of algae bloom with warm water than later in the season. If you get a bloom you'll be slamming and undoing all the time and $ spent

ETA the skimmers are made of a Pvc that seems to be a magnet for iron stains. Your return eyeballs are probably dark brown inside as well.
If we could figure out the exact Pvc compositions of those plastic bits I'd have sheets of draped in my pool and slam away
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
Basod - too late to turn back now. I did the treatment yesterday after work (before you posted) and the results are quite substantial. The ascorbic acid lifted almost all the stains from my liner (with the exceptions of some staining around the skimmers). So far the water still looks crystal clear and I don't see any signs of algae so the polyquat must be doing its job. I took some readings this morning and here's what I got.

FC - 0
TA - 70
pH - 7.1

So tonight I'm going to bring up the pH a tad and then add enough bleach to bring up my FC to 5 (I'll do it over the course of 3-4 hrs to bring it up somewhat slowly). Then I'll turn on the SWG tonight.

Once the chlorine is added, is there any reason my kids and I shouldn't swim????
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
It is safe to swim when
FC is above minimum for your CYA, [FC/CYA][/FC/CYA]
and below shock level
PH is between 7.2 and 7.8
And the water is clear

I would be inclined to turn on the SWG now. It will slowly raise your FC and raise your PH a bit too.
 

samt

Well-known member
May 18, 2013
420
Long Island NY
Another idea where your stains are coming from may be your own city water supply. My small town has a water report twice a year and iron is always listed on the report. I have a white plastic jug I use for watering some small plants with and that jug also has the same color iron stains as my pool. Just a thought.
 

basod

Gold Supporter
May 27, 2015
255
Mount Cheaha Alabama
Just keep an eye on the FC, adjust after bleach addition every few hours, took me ~72hrs - some see many more days before they stop losing FC to AA neutralization

You're in a balancing act now, FC not too high, pH as low as possible, sequestrant doses weekly.

I've been working on getting to a point where sequestrant isn't required -through controlling/filtering fill water, removing stains and getting them out of the pool in one shot, and polishing continuously for preventive treatment
 

jobondur

Well-known member
Dec 13, 2009
182
Virginia Beach, VA
You say add sequestrant weekly, but I thought it said monthly (maybe I'm confusing this with something else). How much should I add weekly/monthly for my 30,000 gallon?

Still losing FC, hopefully that will end soon as I have to leave town next week and the wife's not quite as diligent with regards to the pool. Maybe I'll give it another dose of polyquat before I leave, but how much??? I put in a quart of polyquat 60 prior to starting the AA treatment.
 

basod

Gold Supporter
May 27, 2015
255
Mount Cheaha Alabama
The dosage rating for maintenance will be a balancing act on your part, but the label on whatever you're using(you didn't state the product) should give a week/month dosing.
It will take more in the beginning as you're bringing FC back to normal levels.
Leaving for a while in the middle of trying to play this balancing act is why I posted above on waiting until the water is cooler.... Hey we all live and learn
Whatever Polyquat 60 recommends as a maintenance dose should help, but it isn't going to sanitize while away just help prevent the algae growth - not guarantee no algae growth
 

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