Shocking grren pool NOW IT IS BROWN

grangerhj

Well-known member
Oct 1, 2007
46
Lafayette, La
Help I am just starting getting my pool ready Took the leaf cover off and vaccumed but of course I had a green swamp. So this am I shocked my pool with 3 128 oz 10% liquid chlorine- Kemtech brand. Prior to adding my TC was 0; Ph 6.8; TA 60; hardness 150. did not check my CYA. 3 1/2 hours later I went out- the green was lighter checked the TC and it was 1.5. I again added 3 bottles of liquid chlorine. Went back out 3 hrs later and the pool is brown. The good news is the tc- was 10.5. Early this weekend my husband used some Ascorbic acid to remove stain in pool- which it did. Stain now back. What have I done? I have a 15000 gallon fiberglas pool with a sand filter.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,003
Northern NJ
You undid lifting the iron stains. Adding the amount of chlorine you did precipitated the iron out of the water back onto the surface. The brown in the water is iron.

Here is our recommended Ascorbic Acid Treatment - Further Reading Read the section about how to rebalance after 24 hours.

You can stuff some polyfill from pillows into your skimmers and it should filter out a lot of the brown int he water. You have to redo the AA treatment to light the stains again.

Do you know how you got iron in your water? This may be of help - Iron Fill Water Filter - Further Reading
 

RDspaguy

In The Industry
Mar 21, 2020
582
Cabool, Mo
Is it a clear brown, like tea, or a muddy water brown? I have had pools with alot of algae go brown when the algae was killed and bleached out by the chlorine. I have watched the brown spead through the green from the spot I added my chlorine. If that is what you have, it will settle and can be vacuumed. Just keep the chlorine up, it's ripe for a re-bloom. Turn off the pump for a faster settle.
Ascorbic acid after your water is clear, and the chlorine is 3-5ppm. It will help if your ph and alkalinity are a bit low.
If your stain is recurring in a particular spot this could indicate another issue. Is there anything near the stain?
 

Shirker

Well-known member
Jul 2, 2014
508
Athens, GA - USA
I do not know. I have never checked iron. How would I check?
If you have well water, there is a good chance you do have iron. But you would usually know b/c you have stains on your bathroom/kitchen fixtures. This might be one of the few tests you have to rely on the pools store for. Your local county extension office might be able to provide more accurate testing though. Regardless what the actual numbers are, the link above about how to do Ascorbic Acid Treatment will guide you how to remove the stains. If you do have high iron, raising to shock level probably knocked it all out of solution.

Can you take some good pictures of your pool? That might help trouble shoot. Someone with more experience than me will need to tell you your actual next steps.
 

grangerhj

Well-known member
Oct 1, 2007
46
Lafayette, La
If you have well water, there is a good chance you do have iron. But you would usually know b/c you have stains on your bathroom/kitchen fixtures. This might be one of the few tests you have to rely on the pools store for. Your local county extension office might be able to provide more accurate testing though. Regardless what the actual numbers are, the link above about how to do Ascorbic Acid Treatment will guide you how to remove the stains. If you do have high iron, raising to shock level probably knocked it all out of solution.

Can you take some good pictures of your pool? That might help trouble shoot. Someone with more experience than me will need to tell you your actual next steps.
THANK YOU FOR REPLYING- with the quarantine I am not going to be able to get a sample to a local pool store so if I start the process again I would use the Ascorbic acid, wait 24 hrs and then start to slowly add chlorine (sodium hypochloride liquid) not rapidly to get pool to SHOCK level correct?
 

grangerhj

Well-known member
Oct 1, 2007
46
Lafayette, La
Is it a clear brown, like tea, or a muddy water brown? I have had pools with alot of algae go brown when the algae was killed and bleached out by the chlorine. I have watched the brown spead through the green from the spot I added my chlorine. If that is what you have, it will settle and can be vacuumed. Just keep the chlorine up, it's ripe for a re-bloom. Turn off the pump for a faster settle.
Ascorbic acid after your water is clear, and the chlorine is 3-5ppm. It will help if your ph and alkalinity are a bit low.
If your stain is recurring in a particular spot this could indicate another issue. Is there anything near the stain?
I would not call it a tea brown -of course when I pull a water sample it does not look brown in the bottle? Since I can again see stains along the side what would you opinion be of adding AA with some Polyquat 60, waiting 24 hrs, then slowly add chlorine. or would it be better to add the AA and Polyquat and just let it sit for 3-4 days and then slowly add the chlorine? Will that lessen the chance of the iron pulling our of the water again? We already had plans to change out the sand in my filter as it has been in there over 10 yrs.
 

grangerhj

Well-known member
Oct 1, 2007
46
Lafayette, La
You undid lifting the iron stains. Adding the amount of chlorine you did precipitated the iron out of the water back onto the surface. The brown in the water is iron.

Here is our recommended Ascorbic Acid Treatment - Further Reading Read the section about how to rebalance after 24 hours.

You can stuff some polyfill from pillows into your skimmers and it should filter out a lot of the brown int he water. You have to redo the AA treatment to light the stains again.

Do you know how you got iron in your water? This may be of help - Iron Fill Water Filter - Further Reading
Thank you- I am hopng that by repeating the process and then slowly adding the chlorine and then changing out the sand in my filter ( had been planning to do this since it has been a while since this was done 10+ yrs) that my problem will clear.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,003
Northern NJ
Thank you- I am hopng that by repeating the process and then slowly adding the chlorine and then changing out the sand in my filter ( had been planning to do this since it has been a while since this was done 10+ yrs) that my problem will clear.
Changing sand in your filter will not make any difference with your iron staining. If you plan to do it for other reasons then fine. Sand can last for many years if you have never used pool potions like floc.


The only way to get iron out of your pool water permanently is by draining and filling with iron free water.
 

Shirker

Well-known member
Jul 2, 2014
508
Athens, GA - USA
But.... Before you do anything it might be a good idea to make sure it is iron and not algae. You should probably post updated testing numbers and maybe even do an OCLT test before investing a lot of time/money into removing iron if it is not iron.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,003
Northern NJ
But.... Before you do anything it might be a good idea to make sure it is iron and not algae. You should probably post updated testing numbers and maybe even do an OCLT test before investing a lot of time/money into removing iron if it is not iron.
She likely has iron and algae in the water.

The AA treatment and staining confirmed the iron problem. Algae does not do that.
 
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grangerhj

Well-known member
Oct 1, 2007
46
Lafayette, La
Thank you all It has been about 10 days now and my pool has gone from dark brown to pale green as the chlorine levels dropped. This morning the pool has been vaccumed and I intend to start by adding chlorine and seeing if the level will hold. Once I know the algae is addressed then I will worry about staining. fingers crossed!