Pool Water Turned Brown After Adding Muratic Acid

Stains on the pool surfaces, pool equipment
or on the swimmers, or off-color swimming pool
water. Discolored but clear pool water.
Guest

Re: Brown Water

Postby Guest » Sat 02 Aug, 2008 18:54

I didn't explain the chlorine comment very well. Chlorine oxidizes the iron causing the brown coloring. Although you didn't add chlorine you did add a large amount of muriatic acid.

The muriatic acid lowered the pH into a range where small amounts of chlorine is too much. How much of the chlorine in the water that is in it's active state is dependent on the pH.

For example, at a pH of 8 only 20% of the chlorine in the water is in the "killing form" as it is often called. At a pH of around 6.5, 100 % of the chlorine is in the killing form. When they told you to add a gallon of muriatic it lowered your pH enough to cause your chlorine to react to the iron.

One of the reasons I suggested raising your pH right away was to prevent your chlorine level from continuing to react with the iron. The other reason is that a pH below 7 is acidic and will react with any metal in your system especially the pool heater if you have one.

I believe I suggested raising to 7.2. Having thought about it I would continue to raise it to about 7.8. Once the reaction between chlorine and iron stops the pool will clear sooner.

On a side note, you already have iron in the water so the last thing you need is to add algaecides containing metals (copper).

I was hoping someone else with experience with brown water would chime in here. I've never dealt with turning a brown pool clear but I do understand the chemistry that brings it on.

Follow the directions on the sequestering agent you used. Small weekly doses are often called for.



Chris B wrote:I did not add the gallon of chlorine until after the water had turned brown. My chlorine level was at 1.2, ph was 7.8 and alk was 178 thats when the Watsons clown said to add all the muriatic acid. Thats when the water turned brown. I added the remaining 16oz of the sequestering agent this morning. It seems like the water lightened up a bit over night but not much.
How much is too much when it comes to adding additional sequestering agents? how long should I wait now since I added the second 16oz of the sequestering agent at about 6:00a.m. this morning?
Thanks for continuing to write back by the way, I really appreciate your time and help.


Chris B

Water Clearing Up

Postby Chris B » Sun 03 Aug, 2008 12:53

The water has finally for the most part cleared up :D After adding the gallon of chlorine(liquid), using the GLB Sequa-Sol and washing out the filter every couple of hours the pool has drastically improved. There is still a greenish hue to it but leap years ahead of where it was. I'll continue to add small amounts of the Sequa-Sol sequestering agent per yours and the A-Pro pool store guys suggestion. Thanks so much for all your time and help, I appreciate it so much you continuing to come back and update your helpful replies.

Chris
Guest

Re: Water Clearing Up

Postby Guest » Sun 03 Aug, 2008 18:11

My pleasure. Enjoy your pool and good luck.

Tim

Chris B wrote:The water has finally for the most part cleared up :D After adding the gallon of chlorine(liquid), using the GLB Sequa-Sol and washing out the filter every couple of hours the pool has drastically improved. There is still a greenish hue to it but leap years ahead of where it was. I'll continue to add small amounts of the Sequa-Sol sequestering agent per yours and the A-Pro pool store guys suggestion. Thanks so much for all your time and help, I appreciate it so much you continuing to come back and update your helpful replies.

Chris
chem geek
Pool Industry Leader
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Location: San Rafael, California

Re: Brown Water

Postby chem geek » Fri 27 Feb, 2009 17:16

Pool User wrote:The muriatic acid lowered the pH into a range where small amounts of chlorine is too much. How much of the chlorine in the water that is in it's active state is dependent on the pH.

For example, at a pH of 8 only 20% of the chlorine in the water is in the "killing form" as it is often called. At a pH of around 6.5, 100 % of the chlorine is in the killing form. When they told you to add a gallon of muriatic it lowered your pH enough to cause your chlorine to react to the iron.

Though this is an older thread that got revived by a garbage/spam post, I thought I'd correct a misconception about active chlorine concentration vs. pH. Though the above quoted statements are true with regards to the active form of chlorine, hypochlorous acid, when there is no Cyanuric Acid (CYA) in the water (though at a pH of 6.5 it's 90% in the killing form, not 100%), this is not true when CYA is present. With 30 ppm CYA in the water, at a pH of 8.0, 1.1% of the chlorine is in the killing form while at a pH of 6.5, 3.1% of the chlorine is in the killing form. A comparison of the true graphs without and with CYA are shown in this post . Basically, the CYA helps to buffer chlorine against changes in pH, though it mostly just binds with most of the chlorine so much less is in the active form. This all comes from the science of chlorine and CYA known since at least 1974 as described in the paper in this link .

Nevertheless, this really doesn't matter with regard to oxidation of iron since the amount of active chlorine only determines the rate of the oxidation reaction, not the capacity of whether it gets to completion which is determined by the Free Chlorine (FC) amount (assuming there was more solid iron particles than chlorine). The oxidation of iron is more rate limited by pH than by chlorine concentration so the fact that a smaller proportion of the chlorine is active isn't particularly relevant. It's the low pH itself that is more the cause of being able to oxidize solid iron particles into iron ions. The chlorine helps, but the low pH is the bigger factor. In any event, using a metal sequestrant is the correct prescription, along with filtration to remove bigger particles. I'm glad the problem got resolved and that Tim was able to help -- that's what is most important.

Richard
Daniel Martinez

Pool Water Turned Brown After Adding Shocker

Postby Daniel Martinez » Tue 16 Jun, 2009 10:50

The water in the pool was somewhat clear but it had a greenish tint to it added some shocker to the water
and the pool water turned to a brown color i am in need of some help can anyone help me with this problem
the water after i put the shocker in it was nice and clear and in about one hour it started to change to a brown tint and then it turned to a darker brown

please help
johnmc57

Pool Water Turned Brown After Adding Muratic Acid

Postby johnmc57 » Sat 05 Sep, 2009 13:47

I had the same problem, what you have to do is go to the pool store and buy flock. It is a ganule that when the pump is off will take all iron and make it sink to the bottom of the pool then you vacuum it out.
motel

water well turns brown after using bleach

Postby motel » Mon 26 Apr, 2010 14:30

We have a big problem since a week ago...we have a small businnes motel, all of the sudden while washing sheets and towels they came out brown !!! we have water well system...so...we then realize everytime we put bleach the water turns brown...our swimming pool was clear because we filled it out before...but, a worker here put more water in it and now is brown...we read about the iron in it..and we are trying to find a good filter for the iron...but meanwhile we really need the pool to be clear for the customers to use it... what would be the fastest way to clean it or make it clear...and what are the iron removers? let me know please...we are desperate!!!
prinster21

Pool Water Turned Brown After Adding Muratic Acid

Postby prinster21 » Tue 26 Jun, 2012 22:30

So I know this is a two years later but I seem to have the same water. Though my pool isn't brown right now I put 9 gallons of meratic acid as told by the pool company within a 72 hour period. I still have to buy another chemical starts with a C i forget but. The water is GREEN i mean dark GREEN I just hope it doesn't turn brown. I just bought this house and this is my first pool someone PLEASE HELP!!

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