Help me please with my cya problem

What is floc, clarifier, stabilizer, cyanuric acid,
algaecide, brightener, dichlor, sodium hypo,
sodium bisulfate, ....??
manistyman
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Help me please with my cya problem

Postby manistyman » Mon 31 Aug, 2009 22:39

Hello. New guy here and have registered because I've seen a lot of great knowledge being imparted here. Thank you all.

As for CYA levels being too high, my pool finally went over the top this year after years of puck abuse. I'm in the process of diluting the water in my in-ground plaster pool and my CYA levels are coming down nicely (started today). I've been draining from the bottom of the deep end and adding into the shallow end as well as into the spa (it overflows into the pool).

My question is this: since CYA is heavier than water, would it not be a good idea to let it settle in a calm pool, drain from the bottom, then add to the top? I'm wondering how long it would take for the CYA to settle like this.

Or am I engaged in somewhat wishful thinking?

Any ideas greatly appreciated. Again, many thanks.

Richard 2 (there's a Richard already on the forum, it seems)


chem geek
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Help me please with my cya problem

Postby chem geek » Tue 01 Sep, 2009 00:21

Where do you get idea that CYA is heavier than water? It's like salt that when dissolved in water stays dissolves and well mixed and doesn't settle to the bottom, at least not in something as relatively shallow as a pool. Though you need to dilute the water to remove CYA, removing from the top, from the bottom, from the side, or anywhere else doesn't matter. If you thought that the CYA level differed, then try taking a sample from the bottom vs. the top to see for yourself.

What you are doing is essentially continuous dilution which takes more water to dilute. A partial drain/refill is more efficient, but you need to be careful since some pools should not have their water level dropped too far. In such cases, one can use the sheet or silage bag methods to remove water from under the sheet (or outside the silage bag) and then fill with fresh water above the sheet (or inside the bags).
czechmate
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Help me please with my cya problem

Postby czechmate » Tue 01 Sep, 2009 11:51

To be draining and adding water at the same time is not the best idea.
You dumping part of the brand new water, that you just bought!
Get a sump pump and dump whatever you need, maybe 30%, then add fresh water.
Good stainless pump will cost you about 60 bucks and last you for ever. including your replaster in the future.
You can brush the dust and debris toward it as you pump. and save the filter DE.
manistyman
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Help me please with my cya problem

Postby manistyman » Wed 02 Sep, 2009 09:26

I appreciate the responses with respect to draining and filling, though I am fully aware of the methods used.

As for the "heavier than water" matter, chemgeek, cyanuric acid is heavier than water. I get the idea from basic science. With a specific gravity of 2.5, it's 2.5 times heavier than water (SG = 1.0). I was merely proposing a theory hoping that it might have some validity. For all I know, CYA might stay suspended in water indefinitely, and I did suggest that my theory might be wishful thinking. The tone of your response suggests condescension.
chem geek
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Help me please with my cya problem

Postby chem geek » Wed 02 Sep, 2009 10:56

I am sorry that I sounded condescending and re-reading what I wrote I can see how it sounded that way. The only reason I asked you where you got that idea is that you aren't the first person to bring this up so it's a myth that is propagated by some in the industry. I just wanted to know where you heard it because if it was a pool store then that's one thing but if it's from a manufacturer via a tech. support query, then that's another (and I would call them and follow up on it). In the future, I'll ask it in a different way, such as "Unfortunately, this is not true. Was this information something that came from a pool store or another source?"

The specific gravity you are referring to is for solid CYA. Standard table salt (sodium chloride) has a density that is 2.2 times that of water and sugar (sucrose) has a density that is 1.6 times that of water, but when such substances are added to water they dissolve. Dissolved substances do not settle as their ions or molecules get moved and circulated throughout the solution. There is some effect of gravity similar to that of the atmosphere being denser near the surface, but this effect is only noticeable over much larger distances and only if the water were perfectly still for a very long time. As you said, it was wishful thinking that CYA would be a suspension, but it is not.

Richard
manistyman
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Help me please with my cya problem

Postby manistyman » Wed 02 Sep, 2009 11:14

Richard:

Thank you for your gracious response.

Yes, salt and sugar do have high solubility, whereas cyanuric acid does not. This, combined with its weight, led me to suggest that CYA might have the ability to settle in water -- perhaps in still, uncirculating water and over time.

Just a theory.

Thanks again.
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Help me please with my cya problem

Postby chem geek » Wed 02 Sep, 2009 12:36

I see where you were going, but a lower solubility doesn't mean something will be a suspension vs. full dissolved. The solubility of CYA is around 2000 ppm so much higher than what is found in pools. The slow dissolving of pure CYA is also misleading since the slowness is partly due to the acid being weak. There is a fast dissolving salt of CYA in a product called Instant Pool Water Conditioner that is about twice as expensive as pure CYA, but dissolves readily in water. The primary chemical species in pool water near pH 7.5 is cyanurate ion where one of the hydrogen attached to CYA has been dissociated. This is why the sodium salt of CYA dissolves more quickly since the sodium is removed from the CYA readily, leaving a cyanurate ion. Also, Dichlor dissolves quickly as well, though this adds chlorine in addition to CYA.
apsi pools

Help me please with my cya problem

Postby apsi pools » Fri 04 Sep, 2009 14:07

There is a new product on market which reduces CYA via pulls it out of solution hitting floor. you must vacuum once reaction occurs or staining would occur..
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Help me please with my cya problem

Postby chem geek » Fri 04 Sep, 2009 19:37

Do you have a link to this product? I believe it's just melamine and would create a cloudy mess that takes a while to remove (some would precipitate to the floor perhaps aided by a built-in flocculant). This is similar to what is done in the CYA test itself except that's done at low pH to cause more to precipitate. One couldn't lower the CYA to lower than 30 ppm using melamine in pool water, but that's not bad were it not for the mess. Also, when one tried to increase CYA, it would continue to cloud up again though wouldn't drop quite as much.

Is this what you are talking about? It is no longer available. Or is it this ?
CWMike

Help me please with my cya problem

Postby CWMike » Fri 04 Sep, 2009 22:27

There is reference to a reagent that can reduce CYA ... good read. http://www.ppoa.org/pdfs/PrP_Cyanurics% ... 20Bomb.pdf

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