Which chlorine & why?

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.

Which chlorine do you use in your pool?

Trichlor - granules, tabs, pucks
288
39%
Dichlor
71
10%
Cal Hypo
92
12%
Chlorinating liquid
165
22%
Bleach - supermarket style
122
17%
 
Total votes: 738
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BilliBob
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Which chlorine & why?

Postby BilliBob » Fri 27 Mar, 2009 04:06

I was wondering what folks are using to chlorinate their pools.

Please leave comments with reasons why you use the chlorine that you do.

I use trichlor granules and cal hypo. The trichlor for my stabilized chlorine and then cal hypo. Liquid chlorine always gets watered down where I am so it is an expensive alternative.

BilliBob


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chem geek
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Which chlorine & why?

Postby chem geek » Fri 27 Mar, 2009 12:30

What is the strength of the chlorinating liquid that you say is "watered down" and what is the price per gallon?

I use 12.5% chlorinating liquid from my local pool store which they sell for $3.80 per gallon. This is equivalent to $1.41 for a 3/4-gallon jug of 6% bleach (i.e. Clorox Regular or off-brand Ultra) so is a little more expensive than bleach in my area, but I return the bottles that they then reuse so this is better for the environment than recycling (or trash). My total chemical cost for my 16,000 gallon pool is around $15 per month, mostly for chlorine and a small amount (couple of cups) of acid per month. I have a pool cover so chlorine usage is low at 1 ppm FC per day.

When you compare prices for chlorine, you need to account for the fact that Trichlor requires the use of pH Up product (or Arm & Hammer Super Washing Soda). A cost comparison of chlorine sources is in this post. Bleach can be the least expensive while chlorinating liquid and Cal-Hypo are sometimes comprable, but Trichlor is even more expensive and Dichlor is much more expensive while lithium hypochlorite is out of this world.

Also, don't forget that Trichlor, Dichlor and Cal-Hypo add more than chlorine to the water. The chemical rules that are independent of concentration of product or size of pool are as follows:

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.

With the stabilized chlorine source (Trichlor and Dichlor) the CYA level can build up rapidly unless you have a smaller pool with a sand filter you regularly backwash and have a short swim season with rains that overflow (dilute) the water. The higher CYA level requires a proportionately higher FC level to prevent algae growth unless you use a supplemental algaecide (PolyQuat 60 or a phosphate remover) at extra cost.

Richard
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Which chlorine & why?

Postby Me... » Fri 27 Mar, 2009 21:26

Liquid pool chlorine. In all my years I just can't see anything used so problem free for the most part. Even if it did at first appear to be slightly more expensive, the ease of use should more than make up for that.
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Which chlorine & why?

Postby Guest » Thu 02 Apr, 2009 03:11

I use liquid or bleach because its easy and cheap.
Pooltech32
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Which chlorine & why?

Postby Pooltech32 » Sun 05 Apr, 2009 22:32

If I owned my own pool I would just use liquid chlorine, I service over 100 pools per week and most of them are on a weekly service so I have to use chlorine pucks, but they will raise your CYA levels which can create problems, they will also lower yower your TA over time so you will have to add alkalinity increaser as well
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Which chlorine & why?

Postby Jeffm » Tue 28 Apr, 2009 21:14

I'm glad you posted this, as I've been wondering which one to use also.

So the liquid chlorine doesn't raise TA, CH or CYA at all?
chem geek
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Which chlorine & why?

Postby chem geek » Wed 29 Apr, 2009 01:16

Neither bleach nor chlorinating liquid (nor lithium hypochlorite, which is very expensive) raise either CYA or CH. They only add chlorine and extra salt. All chlorine adds salt since chlorine converts to chloride when it gets used up, but bleach and chlorinating liquid add twice as much salt. For every 10 ppm FC, all sources of chlorine end up with 8 ppm salt, but bleach and chlorinating liquid add an extra 8 ppm salt upon addition so result in 16 ppm salt. However, it takes quite a while to build up salt levels.

For example, even at 1 ppm FC per day chlorine usage, which is pretty low, Trichlor adds 18 ppm CYA and 24 ppm salt per month, Dichlor adds 27 ppm CYA and 24 ppm salt per month, and Cal-Hypo adds 21 ppm CH and 30 ppm salt per month. Bleach and chlorinating liquid add 48 ppm salt per month.

Liquid chlorine will not raise TA over time. However, pools that have evaporation and refill with water high in TA or CH wll have the TA or CH rise over time though adding acid along with normal carbon dioxide outgassing will prevent the TA from rising. So if one uses Trichlor (a very acidic source of chlorine) and has a higher TA level, then one can get to a roughly steady state of TA if there is evaporation and refill. Of course, the CYA will climb.

Richard
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Which chlorine & why?

Postby Bjorn » Thu 25 Jun, 2009 15:53

I use Cal-Hypo and Triclor and I´m aware of the the small consequences... :)
atlantispoolchemicals

Which chlorine & why?

Postby atlantispoolchemicals » Fri 18 Sep, 2009 17:41

Trichlor - granules, tabs, pucks are our most popular type of chlorine. Our current range is the far superior way to keep your pool clean and fresh. poolspachemicals uk
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Which chlorine & why?

Postby chem geek » Sat 19 Sep, 2009 01:57

atlantispoolchemicals wrote:Trichlor - granules, tabs, pucks are our most popular type of chlorine. Our current range is the far superior way to keep your pool clean and fresh.

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. This chemical fact is independent of concentration of product or of pool size. Even with a low daily chlorine usage of 1 ppm FC per day, continued use of Trichlor will add over 100 ppm CYA in 6 months if there is no water dilution. Do you tell your customers that?

As the CYA level climbs, the chlorine (at the same FC level) becomes less effective eventually leading to algae growth. Initially this may appear as an unusual chlorine demand but eventually will result in a green algae bloom. So if you use Trichlor and let the CYA climb and don't proportionately raise the FC level, then you need to use a supplemental algaecide or phosphate remover (at extra cost) and even that will only work up to some point of high CYA. Do you tell your customers that?

If you instead manage your CYA level by using mostly unstabilized chlorine such as chlorinating liquid or bleach (having some fixed CYA level already, such as 30-50 ppm), then you don't need to use an algaecide and don't need to shock regularly. You also won't need pH Up chemicals (at extra cost that actually make Trichlor more expensive that some other sources of chlorine) and with proper setting of TA levels you will only use a small amount of acid. This is, however, less convenient since you need to add chlorine every day or two unless you have a pool cover in which case you can add it around twice a week. Do you tell your customers that?

In my own 16,000 gallon pool shown here, I only use 12.5% chlorinating liquid from my pool store plus a couple of cups of acid every month or two. I have a low chlorine usage of around 1 ppm FC per day because I have an opaque electric safety cover, though the pool is used and open for 1-2 hours every day (more on weekends). This costs me around $17 per month -- that's it (for chemicals -- chlorine prices have recently risen; pump electricity costs are much higher as I have solar that requires higher flow rates).

Richard
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Which chlorine & why?

Postby stacie_stevens » Tue 23 Mar, 2010 23:01

At home I use an Aqua Rite Chlorine Generator. This equipment does all the work for me. It was packaged with a chlorine solution already. With this I no longer need to change the chlorine of my pool frequently. For me, this pool equipment is wonderful!
cburn

Which chlorine & why?

Postby cburn » Tue 20 Apr, 2010 22:48

I have a 15x 30 oval and i use the 3 inch tabs, if i was to switch to a liquid what kind of dosing schedule do you normal maintain. i put maybe 2 tabs in every 2 weeks and use 2 gallons every other week to shock it. i have always had clear water and no alge, sometimes i get clody water but i use a clarifier and some FLOC and backwash and it clears up in a day or so. and help would be great
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Which chlorine & why?

Postby chem geek » Wed 21 Apr, 2010 02:30

If you use chlorinating liquid or bleach then you usually have to add it every day or two. If you maintain higher CYA levels and are careful about dosing, then you can add it twice a week or if you don't care about extreme swings in chlorine level then once a week (which is what some pool services do). If you have a pool cover, then twice a week to once a week is much easier since the chlorine demand is much lower (that's what I do in my pool -- twice a week addition).

There are several automation alternatives for dosing including The Liquidator and peristaltic pumps and of course a saltwater chlorine generator. You can learn more by reading the Pool School.
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Which chlorine & why?

Postby floridapooltech » Tue 18 May, 2010 15:57

It tends to be preferable to many pool owners to use tri-chlor tablets or sticks as this has everything you would need built in. Using a liquid bleach no matter what the percentage, will dissipate much quicker unless you use cyan-uric acid along with it (stabilizer). Also, with liquid bleach, you will need to add muriatic acid along with it as bleach naturally has a high pH. Not doing so will quickly turn your pools pH too high and you will eventually have balance problems in other areas such as alkalinity, etc...Liquid bleach is fine to use (especially for super-chlorinating purposes), but as you can see, it's more work and less cost effective.
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Which chlorine & why?

Postby chem geek » Wed 19 May, 2010 02:09

The bleach or chlorinating liquid will NOT dissipate much quicker if there is already Cyanuric Acid (CYA) in the water. Yes, you should add CYA, but can do so using pure CYA initially. Or one can chlorinate with Dichlor or Trichlor for a while to build up CYA, but then can switch to bleach or chlorinating liquid. It is simply not true that it dissipates faster assuming there is already some CYA added to the water. ALL sources of chlorine produce IDENTICAL chlorine in the water assuming the same water parameters (such as CYA level). Most of the chlorine added to water that already has CYA in it will bind to the CYA while a small amount will remain as hypochlorous acid and hypochlorite ion.

It is also NOT true that bleach and chlorinating liquid lead to rapid and permanently higher pH. Yes, the addition of the products will raise the pH, but chlorine consumption/usage is acidic so the pH drops back down with the net result being close to pH neutral except for the small amount of excess lye -- which is particularly low in 6% Clorox Regular bleach. Technical details about the true pH of chlorine sources is described in this post. I use only 12.5% chlorinating liquid in my pool shown here and here with a daily chlorine usage of around 1 ppm FC (I add it twice a week) and a small amount of acid added every month or two. If chlorine consumption were not acidic, the pH in my pool would rise by 0.3 units per week, but that does not happen as it rises by around 0.1 to 0.2 per month. That's all I add -- about $15 per month in chemical costs for my 16,000 gallon pool. No algaecides, no phosphate removers, no clarifiers, no flocculants, no enzymes, no metal ions, no weekly shocking. There are literally tens of thousands of pool homeowners doing pretty much the same thing using principles originally taught by Ben Powell at The PoolForum and then carried forward at Trouble Free Pool.

You have neglected to tell people the chemical facts that are independent of concentration of product or of pool size as follows:

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 at least 7 ppm.

So even with a low 1 ppm FC per day chlorine usage, continued use of Trichlor pucks/tabs will increase the CYA level by over 100 ppm in 6 months if there is no water dilution. This happened in my own pool 7 years ago as I have a cartridge filter so no backwashing, live in an area with no summer rains, and had a pump on the cover over the winter putting the water in the sewer and not into the pool (so minimal water dilution). The active chlorine (hypochlorous acid) level that prevents algae growth, kills pathogens and oxidized bather waste is roughly proportional to the FC/CYA ratio so if you don't raise the FC level as the CYA climbs then you can get algae growing faster than chlorine can kill it. This is why it is best to use unstabilized chlorine once the CYA level is at a reasonable level to protect chlorine from degradation from sunlight (usually around 50 ppm, though in very hot sunny areas can be as high as 80 ppm, but should not be higher).

One can operate with Trichlor tabs/pucks and high CYA levels if one pays extra for algaecides or phosphate removers and/or shocks weekly, but this is all extra cost. In fact, when one accounts for the cost of pH adjustment when using Trichlor, it isn't always less expensive than chlorinating liquid or bleach on a per FC basis.

Richard

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