Iron in fill water?

[cwmoody]

I just finished remodeling my pool and refilling it. The refill process took three days. As expected, the water turned green since I was unable to run the filter until the water level got over the return jets. Last night I was impatient and decided I would go ahead and get chlorine started and just run the aquabot continuously for circulation. After adding bleach the water turned a dark amber/rusty brown. From the posts I have read, I suspect this may be due to the chlorine reacting with iron in the water. The color changed right after adding bleach, so I don't think it is due to adding bleach with he pump off.

I refilled the pool from city water, not a well. Is iron typically present in city water? How do you test water for iron? I know our city has very old pipes that are in desperate need of replacing and from time to time our bath water will be brownish. If iron, what should I do to combat the iron? I don't want to waste time slamming the pool if I need to be focusing on something else. Below are my test results prior to adding the bleach:

FC 0
CC 0
CYA 0 ?? (I filled the entire tube up and could still see black dot)
Cal 80
TA 20

I added 8 jugs (121 oz each) of 8.25% bleach last night. I ran the aquanaut continuously last night and started the pump and filter this afternoon.

Thanks.

 

[chem geek]

City water can come from ground sources including wells so can contain iron. If you tell me your city or water district I can look up the water quality report and it might say if there's iron in the water. It certainly sounds like that is the case. If it is, then you have several options for either removing or dealing with it, but first let's look at your water report if we can.

 

[cwmoody]

Thanks, chem geek! Jackson, MS 39216

 

[chem geek]

So unfortunately there are two different water systems serving your town and I can't tell which one you are on. This report is for a surface water system while this report and this report are for well water systems, but none of them lists (tests for) iron, but the copper levels are at 0.2 ppm or below. So they don't say much, but you could actually be on well water. Call the number on your water bill and ask the if they know the iron level in the water and if it comes from wells. I suspect it does.

 

[cwmoody]

The lady at the water department looked up my account and said that our supply was not from a well. She did not know any further details of the water makeup though and gave me the number to the water treatment plant. I have called, but have not gotten in touch with them yet.

I read somewhere that high chorine levels can oxidize iron particles causing them to fall out of solution. I believe this may have happened some overnight as there are reddish brown clumps on the steps and floor, especially in front of the returns. Hopefully, when I get home this afternoon there are more clumps and I will vacuum them to waste.

Think it is worth taking a sample to Leslie's to have it tested for iron? Anybody ever had any luck with their testing? I am suspect.

Think it is worth adding some sort of flocculant at this point?

FYI - I added 48 pounds of baking soda and two more jugs of bleach last night.

 

[cwmoody]

Still no luck getting anybody to answer the phone at the water treatment plant.

Just read the article "Metals in the Water and Metal Stains" on TFP. The below statements in that article have me questioning whether it is iron:

"Iron is fairly common in well water but rare in municipal water."

"If the water is cloudy or murky it is very unlikely to have anything to do with metals in the water."


My water is definitely murky. From about 6 feet deep and down, I cannot see the bottom. Was worse than that yesterday, before I had the filter up and running.

I just have never had the pool change so drastically from green to brown. And given that it changed right after adding bleach, I really think the chlorine reacted with something in the water. Also, I let my pool go untreated without the pump running through most of the winter/spring knowing I was going to remodel this spring/summer and this rusty color brown is different.

 

[Texas Splash]

To answer one of your questions above - "yes", going to the pool store to have them test for metals in one of the very few tests we will encourage if needed. Just smile, nod, and walk away when they try to give you advice on the other stuff. Leave your wallet in the car.

 

[chem geek]

The lady at the water department looked up my account and said that our supply was not from a well. She did not know any further details of the water makeup though and gave me the number to the water treatment plant. I have called, but have not gotten in touch with them yet.

I read somewhere that high chorine levels can oxidize iron particles causing them to fall out of solution. I believe this may have happened some overnight as there are reddish brown clumps on the steps and floor, especially in front of the returns. Hopefully, when I get home this afternoon there are more clumps and I will vacuum them to waste.

Think it is worth taking a sample to Leslie's to have it tested for iron? Anybody ever had any luck with their testing? I am suspect.

Think it is worth adding some sort of flocculant at this point?

FYI - I added 48 pounds of baking soda and two more jugs of bleach last night.

48 pounds of baking soda in 45,000 gallons is an increase of 76 ppm TA. Are you sure that's what you wanted to do? You probably don't want to go higher than 80 ppm in TA and I doubt yu started out that close to zero.

There's no sense in testing iron in the pool once you've added chlorine. The iron test kits are useful for testing ferrous iron before it is oxidized, such as testing the fill water. Once you've added chlorine it oxidizes nearly all the iron to ferric iron that then forms iron oxides. So now the approach is to physically remove these precipitates either through vacuum-to-waste, through sweeping to get to the filter (or to skimmer socks or batting material) and then you'll be left over with a smaller amount of iron in the water. At that point you can either use a metal sequestrant or physically remove it with something like Metal Free that tries to capture and precipitate more into the filter or by using CuLator (but call the company if you use that since it may require special instructions). You'll want to remove this extra metal to prevent staining that can occur if the pH rises. Also, you may introduce more metal from evaporation and refill.

I would not use a flocculant nor a clarifier. The iron oxides tend to precipitate well on their own and tend to not stay in suspension.

Your pool is huge so are you really going to be buying and hauling nearly 50 pounds of 12.5% chlorinating liquid or over 65 pounds of 8.25% bleach every week assuming you have 2 ppm FC per day chlorine usage? How did you manage maintaining this pool before the remodel?

 

[cwmoody]

Thanks again for your help with this.

I usually keep the pool on the higher side of the recommended range for TA (70 to 90+). So I did intend to increase the TA that much. In hindsight, I probably should have stepped it up incrementally.

So should I quit adding bleach? Is it better to try to not oxidize the iron and use the Metal Free to help capture the iron in the filter?

Your pool is huge so are you really going to be buying and hauling nearly 50 pounds of 12.5% chlorinating liquid or over 65 pounds of 8.25% bleach every week assuming you have 2 ppm FC per day chlorine usage? How did you manage maintaining this pool before the remodel?

That's the plan. It is actually worse than that. I normally use 6% bleach from my local grocery store. Get a basket full every time I am in there. But I am open to suggestions . . . I haven't had any luck locating a source for higher strength commercial bleach.

The last couple of years the pool was leaking quite a bit of water. During the remodel, I fixed leaks in the skimmer pipe, replaced the entire skimmer, and fixed a large crack that was leaking. In addition to that, when I drained the pool and removed the main drain cover, I discovered that the pool company who was taking care of the pool for the prior owners evidently forgot to replace the hydrostatic valve when they refilled it. The valve was just laying on its side in the drain. Because of the leaks, I have occasionally used trichlor pucks (maybe a few pucks once a month)when I needed to add CYA due to having to refill the pool. Hopefully, that practice can now cease.

 

[chem geek]

So should I quit adding bleach? Is it better to try to not oxidize the iron and use the Metal Free to help capture the iron in the filter?

Metal Free wants you to have a low chlorine level when you add it (around 1 ppm FC) and a low pH (towards 7.2 is best). So you can let the chlorine drop to use the product though may need to use an algaecide like Polyquat 60 to prevent algae unless your pool is naturally low in algae nutrients (phosphates, nitrates). Metal Free binds to both kinds of iron so you don't have to oxidize it all first.

As for your chlorine usage, if it works for you then keep doing it. If you had a pool cover you could cut down your chlorine usage probably by half or more and that would help, but then you'd have a cover to deal with. Keeping sun off of more of the pool will likewise help.

 

[cwmoody]

My pool is in the shade in the morning until about 11:00. I usually average about a 96 oz jug of 6% a day. Which takes my pool up about 1 ppm (makes the math easy!). I wonder if the deeper water helps with the consumption.

Thanks again for your help. I will vacuum to waste tonight. And will continue to trap all I can in the skimmer sock and filter. My wife tells me the water is looking better and more clumps are on the bottom of the pool, so maybe I can beat this without having to use the metal sequestrant. I am baffled that I have never experienced this before given how badly the pool was leaking and the amount of water I was having to add.

 

[chem geek]

What's your Cyanuric Acid (CYA) level and your FC target (that you plan since you're starting fresh)? So fortunately you are only using 1 ppm FC per day so that helps a lot. Yes, maybe the depth is helping -- CYA shields deeper pools better from sunlight.

 

[cwmoody]

I have not added the cyanuric acid yet. Doing that tonight. CYA of 40 and target FC of 5 ppm has seemed to be a good balance in the past, but that may change since my pool is (hopefully) no longer leaking now.

 

[cwmoody]

As an update, the particles continued to settle to the bottom. After vacuuming to waste followed by vacuuming through the filter a couple of times over the weekend, the water has cleared up tremendously. Still a very slight greenish hue this morning, but it appears I have the iron (if that is in fact what it was) whooped. Now I can focus on getting it crystal clear. Thanks again for your help.