Chloramines - conflicting advice - please help

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
Ziora
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Chloramines - conflicting advice - please help

Postby Ziora » Mon 25 Jun, 2007 23:18

I hope someone can help. On the 15, the water started to get cloudy. On the 17th, we couldn't see the bottom, and the water was green. It's been raining off an on. I had the water analyzed at the first pool supply place and followed their advice on the 18th. The water turned a darker green. I live in GA. When we get rain, you know it's raining.

I went to a second pool place today and this is the analysis for our 16x32 pool:
Vinyl pool. Approx. 18,000 gal. Sand filter. 80F.

Saturation Index: -3
TDS: 200
CYA: 125
Tot. Chlorine: 9
Free Chlorine 3.9
pH: 7.1
Tot. Alkalinity: 91
Adj. Total Alk.: 53
Tot. Hardness: 0
Copper: 0
Iron: Not Tested
Salt: n/a

Their recommendations: Follow the advice for chemical adjustments, in the order listed.

Total Alkalinity:
Add 28 lbs. baking soda. The guy said we could add all at once and didn't have to break it up. He said to raise the TA to 125-225.

pH:
Add 4.5 lbs of pH decrease (not muriatic acid). I know the baking soda will raise the pH as we experienced with the last addition of 30 lbs. of baking soda. We have to get the pH to a range of 7.2-7.6. The TA and pH have to be correct before we proceed with the next step (according to the pool guy.) We can worry about the calcium later (again, according to the pool guy.) The dry pH reducer is not supposed to lower the total alkalinty as the muriatic acid will.

Oxidizer:
Add 18 pounds of shock or 15 pounds of the 99% granular chlorine. On the instruction sheet, it says it needs to be shocked to eliminate the combined chlorine. Add directly to pool with pump running. He said we need to do this in one treatment to get it to a breaking point, or it won't work at all.

I am not sure if this is what we should do. The first place told me to put in 4 lbs. of shock, which obviously did not do much. We believe the pool was contaminated with ant killer. The pool guy says that could have caused such a problem. Fertilizers can also do it, if the rain washes it into the pool. Edited: I forgot to say we put an additional 5 pounds of shock. The second water sample was taking about 14 hours later.

I've seen so many different ways of solving this problem. One way is to add the floc stuff. I don't know if we should try the above adice, or try the floc. I swim every day in the summer and love the pool. What on earth is the solution to this mess? We've drained it halfway down and refilled, only to get green mess again a few weeks later.


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Postby Buggsw » Tue 26 Jun, 2007 01:02

You know, with that high of a CYA, I would seriously consider draining around half or more of your water. You can do it like 12 inches at a time, with your vinyl pool.

You won't have to keep your TA so high, you won't have to keep your chlorine levels so high.

The high CYA means you need to get your shock level up to at least 25 ppm and keep it there day and night until it stays at 25 all night long. You will have to add more throughout the day to keep it that high. Once it stays that high, you should have no more algae and no more Combined Chloramines. Which is good.

But with that high CYA, it also means you have to keep your Free Chlorine at a minimum of 8ppm to a max of 16 ppm for swimming, because CYA binds up some chlorine and at that high of a level it binds it up so it's pretty much ineffective at levels lower than 8ppm FC. You will consistently and easily get algae blooms. Lowering your CYA even down to 60-90 will be a little easier because then your FC min level will be 5 and your shock level will be 20.

In the meantime - I would use unstabilized chlorine such as Cal Hypo, unstabilized granular chlorine or liquid chlorine and definitely get that shock level to 25 ppm as explained above.

Not sure about the ant killer - I think it would most likely be so diluted as not to be a problem. Not sure if it would put phosphates in your water as fertilizer would, but you could have your water checked for phosphates. If it's extremely high, you should treat for it. Which will make your water even cloudier for a while. I wouldn't worry about that until you take care of all the other stuff. So put it last on your list of possibles. Then, if you do treat for them, you will want to use a clarifier - some even come with some clarifier tablets you put in your skimmer and vacuum to waste or plan to backwash possibly many times per day if you vac to your filter.

Hopefully Chem geek will be along to address whether the adjusted TA is a problem. I'm not sure about that. Your pH shouldn't be a problem at that level and will rise with a lot of circulation and if you use liquid chlorine. However, you shouldn't let it go below 7.0 with a vinyl pool. But, of course, if you do decide to raise your Alk you will need to lower your pH as prescribed by your pool store.

Once you kill all the algae, your water will still be cloudy for up to a week. Usually, though, it will clear in 3 or 4 days if you keep the pump running 7/24 and backwash as necessary. Vacuum to waste, if you can, that will also help and enable you to add fresh water while you are vacuuming.
Guest

Postby Guest » Tue 26 Jun, 2007 12:59

I forgot to look at the CYA when I was talking to the pool guy. We're draining it down to the intake valve, which is about halfway. I'll have the water retested in the morning, after refilling. I would very much appreciate additional advice once I get the new numbers.
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Postby chem geek » Tue 26 Jun, 2007 13:15

The adjusted TA is just the TA lowered by the amount of alkalinity provided by the CYA. This is only important when computing the saturation index for calcium carbonate which should use the adjusted TA in its formula. When you drain/refill half the water, you'll get a new set of numbers as everything gets diluted except for what gets added back in with the fill water (probably some TA and CH in the fill water).

Anyway, your CYA level was too high and that would prevent you from keeping away algae unless you used high levels of chlorine. You need an absolute minimum of 7.5% of your CYA level as Free Chorine (FC) in order to keep away algae in manually dosed pools (SWG pools can sometimes go a bit lower). The normal target is 11.5% of the CYA level since that gives you a little leeway in case you have unusual chlorine demand. So you need to add more chlorine such that the next time you add chlorine you are reasonably close to the normal target (and certainly above the minimum).

Shocking a pool with chlorine to get rid of algae requires about 40% of the CYA level in order to clear the algae quickly. So you can see why it will be much easier to clear a pool with algae if the CYA is lowered first. Remember that Trichlor tablets/pucks add CYA -- for every 1 ppm FC that they add, they also add 0.6 ppm CYA. Dichlor powder adds even more CYA since for every 1 ppm FC you get 0.9 ppm CYA. Cal-Hypo doesn't add to CYA, but it does add to CH where every 1 ppm FC also adds 0.7 ppm CH. Bleach and chlorinating liquid (and the very expensive lithium hypochlorite) do not increase CYA nor CH.
Guest

Postby Guest » Tue 26 Jun, 2007 17:09

Thanks so much for your kind response. I understand a little more about pool chemistry, I think. Assuming we keep the CYA at around 50, the Free Chlorine should be maintained at 5.75 to be on the safe side. That's quite a bit different from what the last pool place advised. The sheet they gave us said the CYA was ideal at 30-200 and Free chlorine at 1-3. With the numbers they gave us, it seems like there would be a constant battle with algae and a growing demand for chlorine.

I've got to use something different than the Shock Plus by Aqua Chem. It, combined with the granulated chlorine, raises the CYA too much. I'll read back over your post and the previous post. I'm not sure how to translate all the information into actual amounts to add in order to get to the proper levels...yet.

Of course, I could invest in the $1400 ionizer the pool guy wanted to sell, and not worry about the chemicals anymore. :shock:
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Postby chem geek » Tue 26 Jun, 2007 18:12

Anonymous wrote:Assuming we keep the CYA at around 50, the Free Chlorine should be maintained at 5.75 to be on the safe side. That's quite a bit different from what the last pool place advised. The sheet they gave us said the CYA was ideal at 30-200 and Free chlorine at 1-3. With the numbers they gave us, it seems like there would be a constant battle with algae and a growing demand for chlorine.

Yes, you are right. That's why most people battle algae in their pools. Look at all the pool forums with people reporting algae and with only one or two exceptions (with exceptionally high phosphates, and I'm not even sure that's the reason) every pool with algae happened because the chlorine either went to zero or was too low relative to the CYA level.

This isn't really the pool store's fault. They are only passing along the information that manufacturers are telling them that "CYA doesn't matter and only the FC level matters in real pools". This comes from a pool study done in Pinellas County, Florida that I discuss here . I've contacted some manufacturers but most just refer to this study and say that though they understand the chemistry and calculations that I've done, they disagree with my conclusions for "real pools". Decide for yourself.
Anonymous wrote:I've got to use something different than the Shock Plus by Aqua Chem. It, combined with the granulated chlorine, raises the CYA too much. I'll read back over your post and the previous post. I'm not sure how to translate all the information into actual amounts to add in order to get to the proper levels...yet.

There are several pool calculators available on the web including this one . I also have a spreadsheet that does accurate calculations including pH and TA, but it's not for novice users (it's here ).
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Postby Ziora » Tue 26 Jun, 2007 21:49

Thanks to both you and Buggsw for the informative replies. I'm thinking it's better to alternate nonstabilized and stabilized chlorine for shocking and maintenance to keep the CYA at a manageable level, taking cost into account as well as levels. Please correct me if I'm misunderstanding.

I found a few different sites that calculate how much to add of each chemical. I wasn't sure how reliable they were because the results were drastically different from what the pool stores have recommended.

The pool is refilling now, but I'm going to empty it by half again before starting to adjust it. The CYA was so high, I don't think once will lower it enough.

Now I'm wondering about the combined chlorine. If you keep the free chlorine at a level based on the CYA, will it naturally follow that the combined chlorine will be maintained at 0, once everything else is balanced?

Would it be ok to keep posting for advice as things go along? I'm not putting anything in the water until it's done with the second dilution. I never paid much attention to all of this until last month and apologize for so many questions.

Edited to add: The spreadsheet you linked wouldn't load for me.
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Postby Buggsw » Wed 27 Jun, 2007 02:42

You shouldn't use stabilized products at all if your CYA is over 50, IMO.

You really need to keep track of your chlorine and your pH even while lowering your water. Since you already have algae, it will take hold quickly in your new water.

Of course, keep asking away. That's the way you learn.
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Postby chem geek » Wed 27 Jun, 2007 02:50

If one has a small-ish pool (< 10,000 gallons) and has a sand filter they backwash weekly, then using stabilized chlorine (e.g. Trichlor) may be OK as the CYA level may not build up very quickly because of all the dilution. I agree that in general one needs to be careful about it, but in some situations a stable CYA level can be obtained even using stabilized chlorine. I can't do this in my own pool since I have a cartridge filter and its 16,000 gallons, but every pool is different.

As for the link, try this link which is to the same spreadsheet in a ZIP file. The spreadsheet uses macros so maybe it's just warning you about that when you load it. Let me know if it still doesn't work -- this is the first I've heard about this problem.
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Adjusted TA

Postby Ziora » Wed 27 Jun, 2007 22:15

When you look at the TA in relation to the pH, it's not more accurate to consider the adjusted TA? Also, is it 30% of the CYA that you deduct from the TA to get the adjusted reading?

Edited to add: I was able to open the spreadsheet, thanks!

I went to school with someone of the same name. Do you live in GA?

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