blackish flakes after sequestering

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M

MarieB

Silver Supporter
May 15, 2021
27
Murrieta, Ca
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
My plaster had been gaining horrible stains over the last year and tested positive for metal stains with Vitamin C tablets.
I found my FC was at 20!!! Turned off SWG. Took about 3 weeks for FC to drop.
On Friday, with pump on, I took out the remaining 5 of FC with 5 TBSP of sodium thiosulfate. Lowered ph to 7.0 with muriatic acid. Then I put a CuLator 4.0 pack in the pump basket.
On Saturday morning it was cool and cloudy so I completed the ascorbic acid treatment for iron staining and added 64 oz of Robelle Mineral Out sequester. Plaster was so white. :) I let the pool sit overnight.
On Sunday morning I added 5# of baking soda and brought up pH from 6.8 to 7.2 and TA from 50 to 90. pH and TA are still holding.
On Sunday afternoon I left pump on and turned on SWG gradually over 9 hrs, but no FC production happened, so I think I have to replace the salt cell.
On Monday I tried SWG again during the normal filtration cycle of 3.8 hours at 55% and got FC to about .8. I ran pump and SWG at 100% another 4 hours and finally got FC to 1. Definitely need a new cell.

However! I noticed on Monday morning there were blackish flakes resting on the plaster under the returns. I tried to net them out. Plaster is still white, no stain returning. I got a sample tested at pool store and they said my phosphates were 568 !! Phosphates were near or at zero the last several weeks.
Today on Tuesday, FC at 1, pH at 7.2, TA at 90. and MORE blackish flakes underneath the returns.
Question: Are the flakes resulting from the HEDP sequesterant? Are they metal? Are they combination of something? Will they dissolve and restain?

I have to trust that the CuLator pack is absorbing the metal because it is a patented product. I am now going to learn how to clean my filter cartridges!!! Thank you ahead for comments and suggestions!
 

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Welcome to the forum!
@mguzzy has experience with iron. I do find it odd you having an iron issue in S California.

I think you have high expectations from the Culator thing. History here does not show they do much. Once you have the stains off the pool walls, the best way to get rid of the issue is to drain and refill the pool with fresh water.

I suggest you read ABC's of Pool Water Chemistry.
 
mknauss said:
Welcome to the forum!
@mguzzy has experience with iron. I do find it odd you having an iron issue in S California.

I think you have high expectations from the Culator thing. History here does not show they do much. Once you have the stains off the pool walls, the best way to get rid of the issue is to drain and refill the pool with fresh water.

I suggest you read ABC's of Pool Water Chemistry.
Click to expand...
Thank you for your reply. I probably had stray fertilizer inadvertently fall in and perhaps a few grains of iron phosphate snail bait too. Plus, my older toilet tanks are brown inside (!?!) Reading up on basics now!!!
 
Howdy! So I would bet the black flakes are a by product of the sequestrant. You might want to give the company a call and see what their tech support says. I looked up their MSDS and it only says the ingredients are proprietary.. gee thanks that's helpful. It does say it is a blue liquid.. and that may imply some copper content.. I don't know, I'm reaching here.

I don't know if you realize most sequestrants will only bind to the metals that are in the water and keep them there. when the sequestrant breaks down, those metals will be released back into the water. That is why it takes maintenance doses of the sequestrant to keep it in solution. There are a few that claim to bind to the metals and then create a crystalline precipitate to remove the metal from the water (I used Metal Magic on mine) or you can use polyfil to filter it out. Otherwise the only way to really get it out of the pool is to do a drain and refill after the metal has been sequestered. Then deal with your fill water accordingly.

Here are some useful links to send you down the rabbit hole of information overload:

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com www.troublefreepool.com

If you’ve got iron in your fill water, use Polyfill to remove it

EDIT: Found out this method only works if your iron is oxidized already, meaning it’s got a dull or bright green tint to the water, or a nasty brown tint. If you know you have iron in your fill water, but it isn’t oxidized yet, bring your pool to shock level and it’ll turn the telltale green...
www.troublefreepool.com www.troublefreepool.com

What I thought were old iron stains on my cartridge filters, is iron my water!

Hi all Amazingly I found no posts on the forum about this. So I was the victim of the dreaded Iron contaminated Clorox Pool Salt about 3 seasons ago. Apparently it was worse than I thought. There is a nice darker area in my mottled dark plaster in the deep end from salt additions from that...
www.troublefreepool.com www.troublefreepool.com
 
Thank you!! My sequester liquid was pinkish. If the flakes are a byproduct, and I can scoop them out with superfine media, would that mean that I am removing the metals? Do the flakes hold the metal atoms?
 
Did you bypass the heater when you did the ascorbic acid treatment?

AA neutralizes chlorine. Your cell likely is fine, my guess would be the SWG was simply reacting with the AA and not producing chlorine. Until the AA is gone (which it is) an SWG would not produce any detectable chlorine.

As for the CuLator - it’s a waste of money. A company can patent just about anything, that doesn’t mean it actually works.
 
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mguzzy said:
@JoyfulNoise any idea what black flakes could be? Some kind of metal precipitate or just something that fell in the pool?
Click to expand...
I don’t know for certain but I’m hoping that they are the sequestered metals🥴. I’ve been babysitting the pool constantly since weekend, and have never seen anything like that before in the yard or the pool. Except it does look like ash but there have been no wildfires or pit fires. Plus the flakes have sunk down from under the returns. I’m going to hand filter the flakes out with a fine sock tomorrow and call the mfr tech support as was suggested earlier. I wonder if I can test the flakes on the sink and see if they bleach out with vit c? That might prove something....thank you for your thoughts!!!
 

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JoyfulNoise said:
Did you bypass the heater when you did the ascorbic acid treatment?

AA neutralizes chlorine. Your cell likely is fine, my guess would be the SWG was simply reacting with the AA and not producing chlorine. Until the AA is gone (which it is) an SWG would not produce any detectable chlorine.

As for the CuLator - it’s a waste of money. A company can patent just about anything, that doesn’t mean it actually works.
Click to expand...
No there was no option to bypass heater. Aha! Yes the AA neutralized the chlorine because now I am getting FC production! So that means the AA is used up!
On the CuLator I was willing to try! Sounded so good too! Oh well. Thanks for your thoughts!!!
 
Is it correct that sequester is only good for 30 days? I understand that’s why we have to keep adding because it breaks down and releases the metal atoms again. If I get all the flakes out then sequester again and get more flakes then maybe more metal to be had?
I had my filter cartridges cleaned today too and my pool guy said they used to be yellowish brown even after he cleaned them last time. So we thought that maybe the metal stain was removed from cartridges too!
 
I would simply monitor the situation a bit. The black flakes may resolve on their own. Doing an AA treatment with a heater is not good for it. You may have loosened up some build up on the internal copper surfaces and it’s simply flaking off.

I’d stop using that sequestering agent and get a reputable one from Jack’s Magic product line or MetalFree. If your water has iron in it, you’re going to need to regularly use sequestering agents to keep the stains from coming back.
 
Marie
The only way to get the metal out of the pool is to filter it, drain and refill it or use a sequestering agent that produces a by product the causes the metal to drop out. The description of the product you used doesn't indicate it will do that and you just have to add more to keep the iron in solution. So if you want to be sure the metals are removed from you pool, then you should do a drain and refill while the sequestrant has bound to the metals. To my knowledge the only sequestrant that claims to remove the iron in a form that can be filtered is Metal Magic. My thread outlines that process. If you want to filter it out you have to follow the procedure that uses a poly fill filter. The AA treatment does not remove it either it simply releases the iron stains from the walls and puts that iron into solution. I don't think the black flacks are anything but a byproduct of your treatment. It could also be something from your heater core. I just don't know.
 
@JoyfulNoise
Matt, is a sequestering agent such as "Jacks Magic" "The Magenta Stuff" even necessary upon original fill-up/start-up?
What does it do exactly?
If it is not necessary, will it negatively impact the water chemistry in any way or cause any sort of harm?
Thanks much!!
Ron..
 
Usually on fresh plaster startup you want to use a good sequestering agent like Orenda brand or SC1000. All fresh plaster will emit some calcium and so a sequestrant can help reduce the formation of plaster dust. It also helps to avoid metal stains as fresh plaster, especially white plaster, is susceptible to stains. But after the initial 28 day break in period, you don’t really need to continue using it.
 
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JoyfulNoise said:
Usually on fresh plaster startup you want to use a good sequestering agent like Orenda brand or SC1000. All fresh plaster will emit some calcium and so a sequestrant can help reduce the formation of plaster dust. It also helps to avoid metal stains as fresh plaster, especially white plaster, is susceptible to stains. But after the initial 28 day break in period, you don’t really need to continue using it.
Click to expand...
Perfect Matt. Thanks very much for the timely advice. I appreciate it!! :goodjob:
 
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