Looking For A New Chlorine Alternative

[mhugues]

I have recently discovered my CYA creeping up to about 70ppm. I have also recently purchased a Hayward Chlorinator that I would like to keep in use. Can anyone suggest an alternative to Trichlor pucks that will still allow me to use my chlorinator without adding CYA?

thanks in advance,

mike

[coppersnowblue]

You can use bleach, lithium hypo, or cal hypo. Probably won't be able to use that feeder though.

[chem geek]

You can use bleach, lithium hypo, or cal hypo. Probably won't be able to use that feeder though.

And chlorinating liquid, which is just a stronger form of bleach you can find at hardware stores and pool stores.

[waterbear]

I have recently discovered my CYA creeping up to about 70ppm. I have also recently purchased a Hayward Chlorinator that I would like to keep in use. Can anyone suggest an alternative to Trichlor pucks that will still allow me to use my chlorinator without adding CYA?

thanks in advance,

mike

In a word, no. NONE of the other forms of chlorine are suitable or safe to use in your chlorinator. Trichlor is used in erosion feeders because it is the only slow dissolving form of chlorine there is. It cannot be made without CYA since it is a chlorinated isocyanurate, which is a chemical made from chlorine and CYA.

[Dark Helmet]

discovered my CYA creeping up to about 70ppm...alternative...?

You can use bleach, lithium hypo, or cal hypo.

I've been wondering about this too as I've had to empty/fill a pool over high CYA.

CalHypo (cheap shock) seems to have a similar problem in that, while it doesn't jack up CYA, it jacks up CH (Calcium Hardness). And just like high CYA, the only solution for high CH is to drain the pool (AFAIK).

So as to liquid chlorine. Are there any big cons? The one I've read is that hazardous waste cleanups for leaks/spills of fairly small quantities of this stuff can be expensive. Does it oxidize metals or break down plastics its stored in or dispensed through?

Also, one other idea I've read about (a pool book) to possibly get out of the fill/drain/fill/drain cycle with CYA and CH (and reduce required maintenance) is chlorine generators. Namely salt water pool. Was cited as less trouble and cheaper over the long run as salt (the source of chlorine) is cheap, you can run the Chlorine levels higher than a trichlor tabs pool with no problems (e.g. no swimmer irritation), and no CYA is involved in producing the chlorine so your CYA stays stable. The main con cited was only that you have to work harder to keep your pH down. Not sure if you have to fight alkalinity too.

So what are folks opinions? Liquid chlorine or salt/chlorine generators the better option?

[chem geek]

Liquid chlorine, or chlorinating liquid, is simply more concentrated bleach, up to twice as concentrated (12.5%) than typical Clorox Regular or off-brand Ultra bleach (6%). I don't know what you are talking about with regard to hazardous waste cleanups for leaks/spills unless you are referring to tanker trucks with chlorine or something like that. It is no more dangerous in storage than other sources of chlorine in terms of oxidizing metals, but the caps are vented so the chlorine should be stored in a well-ventilated area. Cal-Hypo is far more hazardous for storage, especially if it's high in concentration.

Saltwater Chlorine Generator (SWG) systems generate the chlorine on-site. ALL forms of chlorine result in the identical chlorine in the pool. The only differences are what else they add as you've noted and their effects on pH. SWG pools do tend to rise in pH, but this can be mitigated through a lower Total Alkalinity (TA) level and the use of 50 ppm Borates and a higher Cyanuric Acid (CYA) level if the pool is exposed to sunlight. The main downside to SWG pools is the increased risk of corrosion, but this risk can be mitigated.

I use only 12.5% chlorinating liquid in my 16,000 gallon pool and it costs me $15 per month. The pool's pH is very stable only needing a small amount of acid every month or two. I have an electric opaque safety cover so that keep my chlorine usage low at a little less than 1 ppm FC per day.

Richard

[Dark Helmet]

Liquid chlorine...I don't know what you are talking about with regard to hazardous waste cleanups for leaks/spills unless you are referring to tanker trucks with chlorine or something like that.

Well the writer of the book I was reading mentioned "Most counties and cities will do a hazardous material response and cleanup for as little as two gallons of chlorine. That can cost several thousand dollars. Also with the increasing cost of transporting the chemical due to insurance, I believe the sodium hypochlorite days are limited."

It is no more dangerous in storage than other sources of chlorine in terms of oxidizing metals, but the caps are vented so the chlorine should be stored in a well-ventilated area.

That's interesting -- didn't know that. So a closed pool shed or garage is out I guess.

Cal-Hypo is far more hazardous for storage, especially if it's high in concentration.

I've heard stories from a pool guy that carrying CalHypo shock and trichlor tabs together in a bucket when it starts raining can be an explosive combination, so I could easily believe that.

The main downside to SWG pools is the increased risk of corrosion, but this risk can be mitigated

I hadn't crossed that yet. Can you clarify how that can be mitigated?

I use only 12.5% chlorinating liquid in my 16,000 gallon pool and it costs me $15 per month. The pool's pH is very stable only needing a small amount of acid every month or two. I have an electric opaque safety cover so that keep my chlorine usage low at a little less than 1 ppm FC per day.

Great info. Thanks! I'm surprised your pH is so stable (obviously you've found the trick) as I gather liquid chlorine has a high pH of 13. What's you're secret?

While we're on that subject, I gather from that book that liquid chlorine jacks up TDS a lot, and has a relatively low percentage of free chlorine. Got any comments on that? Do you notice much of a TDS climb? How often do you have to drain?

However, right after that he does say "I like liquid chlorine because it is so easy to use...goes into solution instantly and leaves no visible residue. Great product!"

Thanks for the feedback!

[chem geek]

A chlorine spill of a couple of gallons is trivially easy to deal with. One can just add a reducing agent (chlorine neutralizer such as sodium thiosulfate) and you end up with salty water. I can't say for sure that the guy is wrong, but it doesn't sound right. Now what IS true is that if chlorine mixes with acid you can get chlorine gas and that's a more serious problem as is some forms of chlorine (such as Trichlor) mixing with organics. However, I wouldn't say that makes chlorinating liquid that much worse than other forms of chlorine -- again, it's just like bleach and you don't hear about bleach "hazardous waste" incidents unless it's an entire truck full getting spilled. I presume you aren't going to be taking home more than 4 gallons or so at a time.

A closed pool shed or a garage would be an absolute no-no for Muriatic Acid, which is far worse in corrosion of nearby metal, but chlorine can also outgas and oxidize nearby metal as well -- just not as quickly. Many people do store chlorine in their sheds so its not an absolutely guaranteed problem, but the risk is higher since a temperature rise or metal contamination in the chlorine product can increase pressure in the container and release some chlorine. I keep my chlorine in the pool shed, but it's pretty well-ventilated.

Though it's true that Trichlor and Cal-Hypo (or other hypochlorite sources of chlorine) are explosive or certainly a fire hazard if mixed, Cal-Hypo by itself when at higher concentrations can be self-sustaining in a fire which is what makes it more hazardous. See this post for more info on fire hazard classifications for different types of chlorine.

As for SWG corrosion risk, if you are using soft stone for coping (such as limestone), then sealing the stone will help to protect it. If you have aluminum or weaker stainless steel in the pool, then connecting them to a sacrificial anode (zinc if no aluminum; magnesium if aluminum) can help. Washing off pool equipment where you drip, such as chairs, diving board bases, etc. helps prevent salt buildup and associated corrosion.

Regarding what happens to the pH in pools and spas, you need to understand that the consumption/usage of chlorine is acidic and exactly compensates for the initial rise in pH when hypochlorite sources of chlorine are used (i.e. chlorinating liquid, bleach, Cal-Hypo, lithium hypochlorite). So the pH rises when you add the chlorine, but then drops when the chlorine gets broken down by sunlight or oxidizes an organic or kills bacteria or algae (the chlorine then becomes chloride). Some bleach and chlorinating liquid has some "excess lye" in it for a net pH rise, but not very much. The main source of pH rise is from carbon dioxide outgassing from the pool as pools are intentionally over-carbonated. This pH rise goes faster at higher Total Alkalinity (TA) and lower pH and with more aeration. So lowering the TA reduces the rate of pH rise. This is ironic because TA is a measure of pH buffering, but the carbonates that make up most of TA are also a source of rising pH themselves. Technical details of this is described here. SWG pools have some additional possibilities for pH rise if the chlorine gas that is generated doesn't fully dissolve in the water and instead outgasses. Also, the SWG hydrogen gas bubbles increase the amount of aeration a little bit.

This book you refer to has misleading information in it. First of all, ALL sources of chlorine increase TDS because ALL chlorine gets converted to chloride when the chlorine gets used up or consumed (again, from breakdown in sunlight or oxidizing an organic or killing bacteria or algae). For every 10 ppm Free Chlorine (FC) from ANY source or chlorine, you will end up with 8 ppm salt (measured as ppm sodium chloride) which increases TDS by 8 ppm (PLUS an increase in TDS from CYA or CH which I talk about below). Most hypochlorite sources of chlorine (i.e. chlorinating liquid, bleach, lithium hypochlorite) add an additional 8 ppm salt upon addition so they increase TDS by a total of 16 ppm for every 10 ppm FC that is added. However, TDS that is salt is very innocuous (after all, SWG pools have 3000 ppm salt). It is what TDS is composed of that is much more relevant. For example, the following are chemical facts of what chlorine sources add to the pool that are NOT innocuous components of TDS (these facts are independent of concentration of product and of pool/spa size):

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 Hardnes (CH) by 7 ppm.

Did this book you are referring to mention the above chemical facts? Increasing CH is much more of a problem than increasing salt as a high CH can lead to calcium carbonate scaling. Even worse, increasing CYA reduces chlorine's effectiveness which leads to algae growth unless you use a supplemental algaecide or phosphate remover (or have a lucky pool low in algae nutrients). There are other side effects to the low chlorine effectiveness in terms of sanitation, mostly as it relates to spas, but I won't get into that here. Note that an increase of a few hundred ppm of salt is no big deal; for CH it is worse, and for CYA it's a big problem.

In my own pool, I have fairly low chlorine usage of a little less than 1 ppm FC per day since I have an opaque electric safety cover with the pool used 1-2 hours a day. So the salt (TDS) level increases by 48 ppm per month or by 336 ppm over a 7-month season. That is not a big deal at all. I wouldn't have to dilute the pool for years, but I usually let winter rains overflow the pool since it's free and does dilute from the water whatever contaminants aren't able to be fully oxidized by chlorine. Since I have an oversized cartridge filter I only need to clean once a year and I have little splash-out, there is very little dilution of pool water except for my intentional dilution using winter rains. Even a more normal 2 ppm FC per day usage would be around 700 ppm salt per year (with a 7-month swim season) so would take nearly 4 years with NO dilution to get to 3000 ppm of salt pools (assume you start out at around 500 ppm). Other sources of chlorine would still raise the salt level, but half as fast, BUT would raise the CH or CYA by 300 ppm or 250 ppm, respectively, EVERY YEAR!

As for chlorinating liquid and bleach have a low "% Available Chlorine", this just means that it's heavier to carry, NOT that it's more expensive. Yes, you pay mostly for water, but the price per pound is far lower so what is relevant is the price per FC. Also, with other sources of chlorine such as Trichlor, you have to add pH Up or soda ash / washing soda since Trichlor is very acidic. I give a cost comparison of various chlorine sources here.

Richard

[Dark Helmet]

Really interesting stuff. Thanks. Yeah, the bit about lowering TA to slow your pH rise is counterintuitive and against most "conventional wisdom" you hear and read.

As I've found this last year, there's definitely a lot of "lore" out there in the pool biz making it hard to learn facts. You can talk to two different pool "experts" and get the exact opposite read on pretty much everything except chlorine. Heck, I've even had one tell me nothing matters "except" chlorine. Though I realize the fallacy of that.

Did this book you are referring to mention the above chemical facts?

Some, but not all of them and sporatically. While he mentioned that trichlor tabs are half stabilizer, and occasionally comments on the affect of something to TDS, it's not a thorough and compete treatise.

It's written by a career pool guy, not an engineer. Lots of good stuff to give the new pool owner or maintainer some guidelines and a working framework (great starter book), but now I'm ready for a "pool maintenance from an engineer's perspective". Got any recommendations?

[Pool-newb]

Recommendations? Yep. You're here.

I started my pool career about a year ago with a vinyl lined swamp.

While I am by a long shot no professional, after reading through the Pool School and using the Pool Calculator (links in my signature) I was soon able to understand and control my pool water condition.

I had exactly the same problem you do with the CYA, plus another problem with pH being constantly too low (previous owners completely rusted out the heater and lead in/out pipes) , and it was all caused by using the pucks in a feeder.

The pucks are very low pH but anything I added to raise the water ph also raised the TA. Pretty soon I had such high TA that the pH wouldn't do anything but stay low, and by then the CYA was higher than the test kits can measure.

I got the CYA down to about 60 by draining a foot or two on closing, and replacing that with rainwater on opening. The CYA then suddenly crashed - apparently due to a soil bacteria contamination when a plumbing failure had stopped all circulation for several days.

I lowered the TA by aeration - I put the blower side of a clean shop-vac on a weight so the end blew huge bubbles into the pool, and kept the pH low while the bubbler was running. That causes the TA to outgas as carbon dioxide.

To make it stay right I removed the erosion feeder from the plumbing and began using bleach from Walmart or Home Depot. This method required a little bit of muriatic acid every few weeks or so, and it was irritating to add the bleach every few days, but it is effective and probably the best cost solution there is.

I recently converted to an SWG but I have no special plumbing, hardware or stonework that will be damaged by the salt water. I paid about $900 for a basic, high output SWG but if you want something very automated and still want to use bleach, there are pumps available with ORP sensors that can automate the job quite nicely in response to demand. I've seen completely automated systems for bleach and muriatic acid for $2000 - $3000.