Green Water after Chlorine Addition

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kgturner

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Apr 5, 2014
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Mobile, Alabama
So I'm pretty sure I know what's happening. I did the ascorbic acid treatment in my pool about a month ago because my steps were yellowed. I followed all the steps, except the part where I add sequestrant. After I started adding chlorine, the water turned a pale green. I assumed it was causing the metal in the water to precipitate out after mixing with the chlorine. On 2-15-16, I bought $50 worth of sequestrant and the green cleared up. Last week, I started checking my levels in advance of prepping the pool for open toward the end of next month. My initial readings were:

FC 0
CC 0
pH 7.3
TA 40
CYA 0

I have since added about 6 lbs. of CYA to bring that level up, about 8 lbs. of baking soda so that my TA is around 65-70 right now, and about 2.5 gallons of chlorine spread out over the week. This morning, I noticed the deep end is greenish. After getting home from work, the pool is now pale green again. I assume I can dump more money into sequestrant, but what would happen if I did nothing? Wouldn't the stairs just yellow again? The pool looked great last season except for the yellow stairs. If I'm gonna have to spend an extra $100 or so a month on sequestrant, I'd rather just have yellow stairs. On that topic, do those CuLator packets really work?

Kevin T
 
Since you are no stranger to metals in the water, I agree and suspect that not only did the chlorine make the metal precipitate, but may also cause the stairs to change color just like last season. But before going to much further, I would simply to let the chemical levels adjust from what you've recently added. Let the CYA show a good reading in a few days and re-check all the levels one more time so you know for sure where you stand chemically. The fact that your water had 0 FC and 0 CYA can make for some whacky conditions, so that's why I would recommend ensuring you can balance the pool the TFP way first (hold FC levels as well each day), then if needed later, consider your sequestrant options.

I have no personal experience with the CuLator packets, but I'm sure someone else will chime in.
 
Yes then, before adding any sequestrant, I would continue to balance. The high CC is indicative of the transition process happening in your water and you may very-well need to SLAM. Don't add any more stabilizer just in case so that if you do have to SLAM you can maintain a lower FC shock level. At this point, I would adjust pH to 7.2-7.4 (pre-SLAM) and consider performing an OCLT. I'm fairly confident the OLCT will confirm you need to SLAM, but it would be good to know for sure. You'll want that water algae-free before trying to do any further water management. Best to confirm which type of "green" you are fighting. :)
 
Added 2.5 gallons of 10.5% last night around 6:30 p.m. and tested the water about 7:20 p.m. Readings were:

FC 14.5
CC 1.5

I did the OCLT test, but I must've not waited long enough last night because this morning around 6:30 a.m. my readings were:

FC 17
CC .5

I went ahead and tested everything else. Currently:

pH 7.9-8.0
TA 90
CYA 45-50

I've been battling pH since last season. I keep bubbles in my pump basket lid so obviously there is an air leak somewhere that I have yet to find. I checked everything I could think of so I'll probably have to call a repair company to finally get the air leak solved/fixed. Here's a shot of my pool this morning with the sun behind me at 9:45 a.m. Needs a little Nautilus-ing. There's no visible algae anywhere that I can see in the pool. That's why I think the chlorine is causing the metal to precipitate out.

Kevin T
 

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Hey Kevin...we have the same pool! And the same metals problem. Yours looks like algae. After the AA treatment you may have waited too long to get the FC up. After the AA treatment it's a bugger to get the FC back up. As far as your PH reading it will be unreliable with a FC higher than 10.

I have found because of metals I have to keep my ph lower around 7.2 with lower FC. Any higher and the metals come back. I just try to keep my levels where I never need to slam. After my first AA I also missed the part about adding seqestrants and battled it all summer. Before I open in a couple of weeks gotta do it all over again. It sure is hard to beat!
 
The water is green and clear at this point so I assume it's the metal. It was slight green yesterday morning and noticeably green yesterday evening. I've never known algae to take over that fast, especially since my water temp is 60-62 F. Plus, there are no blooms in the corners of my pool where I see algae usually begin. Trying to decide how much effort I want to put into fighting yellow steps at this point. May try to the sequestrant / CuLator route if I decide to do battle. Otherwise, I may just throw in the towel for this season and try again next year. I still have a couple pounds of ascorbic acid in my pantry.

Kevin T
 
First, forget the culator. It removes metals but the capacity isn't adequate. To buy enough to get rid of the metals, the cost goes way, way up.

So, iron is in your water and WILL STAY IN YOUR WATER FOREVER either 1) in solution or 2) precipitated out onto your walls.

You can get rid of it by changing your water source. (Refill with iron free water, using replacement water from a water softener, R/O)

Otherwise you can just live with it by spending some money on sequestrant and carefully monitoring all your parameters.

All hard choices but an iron-laden pool is a real pain.
 

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Kevin, the steps may discolor again like last year, but the amount and exact location of staining could change depending on the chemistry at the time. As you already know, managing a pool with metals is a bit of a challenge. But before you try this season, you must make sure your water is algae-free. Your past set of results in post #5 indicate you are not quite there yet. I would highly encourage you to continue with the SLAM until you pass all 3 SLAM criteria, then you can look at sequestrant additives. If you add sequestrant too soon and find your pool still has algae, you'll end-up increasing FC again and defeating the purposes of the sequestrant. And don't forget .... your pH will be high because of the high FC, so don't bother testing pH until the SLAM is done. Save your reagents.
 
It will precipitate back out onto the steps and skimmer if you fail to keep sequestrant in the pool (it "wears out").

The iron is in your pool either as a solid (on your steps) or in solution controlled by sequestrant and pH. Hard choices.

EDIT: I just saw Texas Splash's post.....he is absolutely correct. Make sure your algae is gone and you have all your parameters in good order. After you have accomplished that (and it may take a while), only then should you address you staining.
 
At this point, I'm attempting to SLAM so messing with TA isn't on the horizon until I'm done with that. I just don't know where to turn to next once I'm done SLAM-ing. TA? Metals? My wife thinks we should just drain and refill, but I'm not so sure.

Kevin T
 
Kevin, based on your water bill, you could probably estimate how much it would cost to drain your 20K pool versus several gallons of bleach. But also important is the stability of your ground. Many pools have lifted or encountered structural issues when drained, so be sure to keep that in mind when you discuss. The SLAM will of course clear the algae, but any metal will remain unless you have a metal-free source to refill. If you chose to keep the water, I would simply continue with the SLAM then adjust the other levels afterwards. They will be fine until then.
 
Not certain what's in my fill water. It's not well water. I'm on city water. I have a septic system so water should be cheaper, ie no sewage fee. Just looking at my pool, it appears that the stairs are starting to yellow again. The wife suggest I just throw "something" else into the pool for the metal (iron?) to bind to. Pretty sure it's not that easy. Maybe I can find a ton of blonde wigs for the iron to leach onto. ;) Guess this just may be a battle for another time as I still have to find where my suction side air leak is and get that repaired. Both return jets constantly blow bubbles into the pool which I assume is what's causing my pH to continue to rise via aeration.

Kevin T
 
After you finish and pass the SLAM, I would go back and re-read the link pooldv provided in post #7 about metals in the water. Once the algae is confirmed to be eliminated, you can control the side effects of metals in the water. Yes, that may require a sequesrant for the metals to "bind to" as your wife noted, but the water chemistry must be correct first.

If you have any doubt about your fill water (source), take a sample to the pool store and see what they say about metals - if there are any. If they say none, then perhaps it's from something else added to the water in the past. Some pool store products can do that. Post back when you pass the 3 SLAM criteria and we'll do what we can to help you further.
 

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