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A BBB guide to supermarket poolcare.
Use store-bought bleach, baking soda
and borax to replace proprietary pool chemicals.
chem geek
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Postby chem geek » Sat 12 Sep, 2009 13:04

(...continued from above)

pH of Chlorine
What do you mean by your saying you are a "water chemistry tech"? If you know chemistry, then you would know that for the equivalent amount added to achieve a specific Free Chlorine (FC) level, Cal-Hypo has the pH rise upon addition the same as bleach, chlorinating liquid, or lithium hypochlorite. ALL hypochlorite sources of chlorine are high in pH and raise the pH upon addition. Also, regardless of the source of chlorine, when the chlorine gets used up, either by oxidizing an organic or by breakdown in sunlight, the process is acidic and for hypochlorite sources of chlorine the pH goes back down to where it started. The chemistry behind this is described here. Because of the acidity of chlorine usage/consumption, Dichlor is actually not near pH neutral but is net acidic and Trichlor is even more acidic than upon initial addition.

Look at any Cal-Hypo MSDS such as here and see that the pH isn't neutral, but 10.4-10.8 for a 1% solution (a 10% solution would have a pH of around 11.5) while Clorox Regular unscented bleach at 6% is around 11.9 (see here) and 12.5% chlorinating liquid is typically 12.5. So chlorinating liquid has the most "excess lye" in it, but even so this only results in a net rise of 0.1 pH units per month at 2 ppm FC per day chlorine usage.

In my own pool I use only 12.5% chlorinating liquid I get from my local pool store (since it's at a decent price and they reuse the bottles so is better than recycling). The pH in my 16,000 gallon pool (shown here) is very stable with my adding a couple of cups of acid every month or two. If the pool were not used every day (1-2 hours weekdays; longer on weekends), the pH would be even more stable. The primary source of rising pH in pools using hypochlorite sources of chlorine is the outgassing of carbon dioxide and this can be minimized by having a lower TA level (with a higher CH or target pH as needed to keep the saturation index near 0 in plaster pools). There is a small amount of "excess lye", but this contributes only to a rise in pH of 0.1 in 2 months in my pool; the other 0.2 units of the pH rise is from CO2 outgassing. Because I have a pool cover, my chlorine usage is fairly low at around 1 ppm FC per day. This costs me around $15 per month, period. And, by the way, the pool has 2000-3000 ppb phosphates due to 300-500 ppb phosphates in the fill water plus other sources, yet the pool stays algae-free using chlorine alone.

Strength of Chlorine Sources
Clorox Regular Bleach and off-brand Ultra bleach is normally 6% (off-brand regular bleach is often 3% or less). It is chlorinating liquid that is 10% or 12.5% (14% is more rare). However, all such percentages mean is the amount of chlorine PER WEIGHT of product. It has absolutely nothing to do with the effectiveness of the chlorine in the water. You simply have to add more bleach or chlorinating liquid by weight (and volume), but it's also much less expensive by weight such that overall it is comparably priced or sometimes less expensive than Cal-Hypo. A comparison of the true cost of various sources of chlorine is given here.

Side Effects of Chlorine Sources
Cal-Hypo will increase the Calcium Hardness (CH) so if the CH is already low then using Cal-Hypo is OK, but if the water is already saturated with calcium carbonate to protect plaster, then one should be careful about using too much Cal-Hypo. The following are chemical facts independent of concentration of product or of pool size and are not taught in NSPF CPO nor APSP TECH:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.

Some simple calculations show that even with a low chlorine usage of 1 ppm FC per day, continued use of Trichlor increases CYA by over 100 ppm in 6 months if there is no water dilution. Likewise with Cal-Hypo the CH increases by over 125 ppm in that same period of time. With an uncovered pool, typical chlorine usage can be double these amounts (i.e. 2 ppm FC per day).

(to be continued...limit of 5 URLs per post)


chem geek
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Postby chem geek » Sat 12 Sep, 2009 13:05

(...continued from above)

The Chlorine/CYA Relationship
There is no question that killing algae requires chlorine, but the level of chlorine needed, that is the FC level, depends on the CYA level because the amount of active chlorine (hypochlorous acid) that kills algae is proportional to the FC/CYA ratio. The original definitive source for the equilibrium constants defining the chlorine/CYA relationship was published in 1974 in this paper. The derivation of why the FC/CYA ratio is a decent proxy for chlorine activity at pool pH is here. To prevent green algae growth in non-SWG pools requires a minimum FC of around 7.5% of the CYA level while for SWG pools the minimum FC is around 4.5% of the CYA level. This minimum includes the overnight loss so in practice in SWG pools with 80 ppm CYA a minimum target FC during the day is around 4 ppm.

Phosphates
Phosphates (source of phosphorous) are one of several possible limiting factors to algae growth. Others include nitrates (source of nitrogen; also nitrogen gas for cyanobacteria), carbonates and carbon dioxide (source of carbon), water, sunlight and temperature. Phosphate removers only remove (inorganic) orthophosphate so if there are small organic phosphates in the water then algae can still grow, though more slowly. Chlorine can kill algae faster than it can grow in spite of high phosphate and nitrate levels since there is a limit to such growth due to sunlight and temperature where even in the best natural conditions it takes algae 3 to 8 hours to double in population. When chlorine kills the algae faster than this timeframe, it doesn't matter how many nutrients there are in the pool.

Phosphate removers need to be seen in the same vein as algicides such as PolyQuat 60 or 50 ppm Borates or even copper. These are not necessary, though they do provide insurance to slow down algae growth if the chlorine level is not managed properly and gets too low.

Much more can be learned by reading the Pool School.

Richard
PoolPro

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Postby PoolPro » Sun 13 Sep, 2009 03:12

samanthathepoolchick does not know what she is talking about. I recommend that everyone ignore her advice.

Don't be concerned about phosphates. Liquid chlorine is a better source of chlorine than calcium hypochlorite. Calcium hypochlorite contains other elements, besides just calcium hypochlorite, that do increase the pH, such as Calcium hydroxide and calcium carbonate.
czechmate
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Postby czechmate » Mon 14 Sep, 2009 20:37

Maybe cleaner chlorine, not necessarily better.
For fast, effective shock it hardly beats 73% Calcium Hypochloride.
If you need to shock 25 000gal pool that has a 100ppm CYA and 2ppm of AC, no professional will even consider trying to start messing with a pallet of bleach bottles.
Certainly the kitchen bleach has its advantages in normal pool maintenance, but there are limitations.
(You can drive 93 octane built engine on 89 octane also. But it's computer will retard the combustion process and at the end you will loose mpg and the spunk, without saving a dime).
chem geek
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Postby chem geek » Mon 14 Sep, 2009 21:48

czechmate wrote:If you need to shock 25 000gal pool that has a 100ppm CYA and 2ppm of AC, no professional will even consider trying to start messing with a pallet of bleach bottles.

That's very true, but if the CYA is at 100 ppm the proper prescription is to start water replacement right away if possible since that has to be done anyway. It all depends on how long the pool has had the algae. If it's already long-gone, then water replacement first is better. If it's just started it's algae bloom, then hitting it hard right away with chlorine is better to prevent it from getting worse and if it's more convenient to use Cal-Hypo, then so be it.

Just keep in mind that for every 10 ppm Free Chlorine (FC) added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm. So for a short-term shock, this isn't too bad and of course is no problem at all if the CH is low (say, because it's a vinyl pool). Even hitting hard with 40 ppm FC would be a CH increase of 28 ppm which is most likely not a problem unless the CH is already too high. Since one would be diluting the water anyway to lower the CYA, getting the CH a little too high isn't a big deal. One can always lower the pH first to help compensate for the saturation index anyway.

I wasn't disputing the use of Cal-Hypo per se, but rather the implication that it didn't raise the pH upon initial addition or that it's greater strength meant it was more powerful in the water.
PoolPro

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Postby PoolPro » Mon 14 Sep, 2009 23:21

______________________________________________________
czechmate wrote:
"For fast, effective shock it hardly beats 73% Calcium Hypochloride.
If you need to shock 25 000gal pool that has a 100ppm CYA and 2ppm of AC, no professional will even consider trying to start messing with a pallet of bleach bottles."
____________________________________________________

You do not know what you're talking about. What is "Calcium Hypochloride"? What is "2ppm of AC"?

If the pool is already cloudy, the last thing you need to do is cloud it up more with a lot of calcium hypochlorite. Calcium hypochlorite does not dissolve well under good circumstances; it certainly will not dissolve well when you begin chucking it in by the bucketful.

Liquid chlorine or bleach is a much better choice. It will not take a pallet of bleach.

Also, your car analogy is worthless and meaningless.
PoolPro

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Postby PoolPro » Mon 14 Sep, 2009 23:38

czechmate wrote:But it's computer will retard the combustion process


It's not the combustion process that's being retarded.
czechmate
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Postby czechmate » Tue 15 Sep, 2009 08:26

Of course I do not know what I am talking about.
I am deeply sorry for hurting your ego, Mr. Professional Pool Man!
Question: Are you the missing pool man???
samanthathepoolchick
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Postby samanthathepoolchick » Tue 22 Sep, 2009 13:13

PoolPro wrote:samanthathepoolchick does not know what she is talking about. I recommend that everyone ignore her advice.

Don't be concerned about phosphates. Liquid chlorine is a better source of chlorine than calcium hypochlorite. Calcium hypochlorite contains other elements, besides just calcium hypochlorite, that do increase the pH, such as Calcium hydroxide and calcium carbonate.



I did not come to this forum to be insulted just to help people as best as i can and to tell everyone to ignore my advice? I would like to know what qualifications POOLPRO has in water chemistry or in the industry at all???
PoolPro

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Postby PoolPro » Tue 22 Sep, 2009 21:38

samanthathepoolchick wrote:The BBB method is no good.

and

I did not come to this forum to be insulted


I am not insulting you any more than you are insulting the BBB method and everyone who believes in it. The BBB method is used successfully by many people. I doubt that you even understand it. I have every right to defend it and the people who believe in it.

I don't mean to insult you; however, if I think that your advice is no good, then I have every right to say so. It's called peer review, and it's a legitimate process of quality control. I am sure that I know much more about chemistry than you ever will.

You think that you get to challenge and criticize someone else's advice but no one can challenge or criticize yours? That's not how it works. If you want to publish on a public board then you have to accept the commentary that might come as a result.

You are the typical pool industry stooge who just parrots the big chemical industry nonsense to sell a bunch of over-priced, but useless, chemicals. Most of the pools that you take care of are probably green despite you adding tons of algaecide, floc, clarifier and phosphate remover. You use too much trichlor and cal-hypo, which causes your customer's cyanuric acid and calcium levels to go sky high.

samanthathepoolchick wrote:I will start with why you should not use Bleach it has a PH of 13, right now your PH is good. You will need to Shock though i would give you a calcium hypochlorite shock one pound per ten thousand gallons.


You advice to avoid bleach due to its having "a pH of 13", proves that you do not understand the chemistry involved. It is further proved by you then advising the use of calcium hypochlorite, which has the same effect on pH as bleach would

samanthathepoolchick wrote:Have the pool store also check your phosphates this could also play a role in the green.


More bad information. When your customer's pools turn green, you probably use every excuse in the book. Filter sand needs to be changed, high phosphates, needs algaecide, blah, blah, blah.

samanthathepoolchick wrote: I would like to know what qualifications POOLPRO has in water chemistry or in the industry at all???


What qualifications do you have? I can say anything I want and so can you. I judge people by the intelligence of what they write, their ability to support what they say, their logic etc. I can tell who knows what they're talking about and who's full of crap.

Bottom line: Give good advice and no one will have to challenge you. If you legitimately think that someone is giving bad advice, then it's your duty to say something. My opinion is that your advice is no good.

P.S FYI: Just because a couple of your paper route customers pay you an extra $10.00 a month to scoop leaves out of their pool does not qualify you as a service tech.

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