A 'SALT WATER' POOL
CHLORINE PRODUCTION IN YOUR SWIMMING POOL
BY 12 VOLT ELECTROLYSIS OF COMMON SALT

A NEW ZEALAND INVENTION THAT HAS SWEPT THE WORLD!

Cascade pioneered Salt Water chlorination devices in 1972
By LE Ogden - NZMPB Diploma Pool Technology

WHEN DID IT ALL START?
After a chemistry major friend mentioned to me in the late 1960's the feasibility of producing a Chlorinator - a chlorine device to produce chlorine in home pool water to avoid the need of pool-owners regularly handling dangerous chemicals such as Calcium Chloride.

Calcium Chloride is normally stable but is a dangerous chemical potentially capable of causing eye and lung damage (if inhaled). Although not easily combustible, inadvertly spilling oil or other mixtures found in household garages (where it is typically stored) can be traced to causing fires.

So the idea of eliminating this unpleasant chemical by developing an alternative method of chemical delivery being developed was interesting. I worked on a shape size and colour for such a device, and experimented with alternatives for several years, resulted in finally - in October 1972 - the final design and colour scheme had been produced and testing completed. The result was the IG450. IG (for In Ground pools) and 450 (for 45,000 gallon pools)

Having spend years in the 1960's UK and the eastern States of the USA learning the home swimming pool industry, I was satisfied that I had created a device that would revolutionise the home swimming pool industry.

Something that (to the best of my knowledge and belief) having spent years in European and US markets, I had never seen or had any prior knowledge of usind electrolysis to produce sodium chloride into sodium hypochloride. Over the years, I have googled to see if anyone else was marketingSalt Chlorinators to the World Market, and apart from a few other attempts from inventors, I found no other manufacturer in the early 1970's

For the southern hemisphere 'Summer of 1973', my company Cascade Industries introduced the Aquatech IG450 Salt Chlorinator - a unique device which created sodium hypochlorite (liquid Chlorine ) from a 2% (20,000 ppm) salted pool water by passing the water through a 1-1/2" (40mm) clear PVC tube encasing a 12 volt DC multi-plate stainless-steel-mesh electrode as part of the filtration system's 'return-to-pool' line! A World First!


IN 1973 THE IG450 SOLD FOR $695 !!

When the typical small 12' x 24' family pools (3.6m x 7.2m) were selling for less than $1,995.00 installed, this was expensive (!) - but proved to be a great improvement over the huge $250 "one hundred pound" (35 Kg) drums of HTH granular pool chlorine we included with Cascade pools in those days.

At that time in New Zealand it was illegal to repack powder (Granular) chlorine into smaller packs, and the HTH brand granular chlorine could not even be stocked in drums or sold without a Dangerous Goods license, so customers had to take the full size drum. There was a problem trying to keep tightly sealed, and as the chlorine gas emmitted when the lid was constantly being removed, itwas extremely hazardous. We provided a plastic Scoop and Gas Mask with every drum of HTH! The instructions were to tip the scoop of HTH into the Skimmer while the system was running, as tipping it ito the pool would cause damate to the pool interior.

The IG450 units had stainless steel four-plate electrodes - which eroded within two to three years, and $250 to replace was a high cost in those days. Later models (the IG450P) used a Platinum electro-plated stainless steel electrode which lasted two to three times as long (but cost twice as much to replace)

In 1974 we introduced polarity switching (I think it used a HEXFET - and Metal Oxide Sintered Field Effect Transistor MOSFET but that may have been later in the production run) which reversed the DC + 'Positive' and - 'Negative' (DC) current every minute or so. Reversing the polarity dumped the accumulated gunk off the electrode giving the "appearance" of an extended service cycle between acid washes, and was sold as "Self Cleaning" (This description continuing to this day by other suppliers of Salt Chlorinators) but of course it was a "have" - the dumped gunk soon reattached itself!

The polarity reversing idea seemed good at the time, but unfortunately the cell gradually continued to build up a thin coating of calcium "from shock dosing periodically with Cal Hypo - which inhibited the production of chlorine, so they still had to be periodically dismantled and given a bath in dilute hydrochloric acid to "freshen" them up.

The polarity switching is still being used by Salty manufacturers today, but as stated it is a short term solution to the problem of calcium buildup and gradual deterioration of the electrode.

Sodium Hydroxide (aka Caustic Soda - commonly sold as 'DRAINO' drain unclogger)
It wasn't until many years later (1994, in fact) that we fully appreciated the chemistry the pool water.
After all, the pools 'never went green' and everybody was happy!

Unfortunately, the old saying 'no free lunches' came true.
We were 'structural engingeers' building swimming pools NOT chemical engineers!

We had overlooked the production of sodium hydroxide (Caustic Soda NaOH) - being equal in quantity with the sodium hypochlorite production - and as a consequence, the pool pH was always extremely high. as the pH of Caustic Soda tops out at 14 (on a scale of  0 - 14) and Sodium Hypochlorite has a pH of 11.0 - 13.0

The pool pH rose so high, in fact, that the sterilisation of the pool is in jeopardy, as once the pH exceeds 8.0 there is literally no effective sanitisation taking place, and the pools were constituting a health & safety risk to the users if the pool owner was unaware of - and did not take action to reduce - the high pH situation! Dosing the pool with gallons of Hydrochloric Acid became a necessary and regular task!

Our final version IG450A incorporated an acid pump to remedy this situation, but the unit cost soared to $2,800.00 plus the cost of the 40 litre drum of hydrochloric acid which was inconveniently located adjacent to the pool filtration.

The presence of such large quantities of dangerous acid also posed a questionable risk to children who might have access to the filtration area.

After Twenty-one years of selling 'Saltys', Cascade abandoned the idea of providing a Salty with every pool!

Seeing this as an extreme safety hazard for young - and curious - children, in 1994 we discontinued the installation of salt chlorinators in favour of the US made Aquagenie Skimmer/Feeder system - which we still use today and 2002 in conjunction with an activated oxygen generator (Ozone or O3) or PROZONE unit.

Other problems we encountered with salt water pools includes premature corrosion of pool equipment and pool surrounds, the need to top up with heavy 25kg bags of salt as rainfall dilutes the pool water, and the need to periodically acid wash the electrode to remove calcium coating which reduces the performance of the unit.

Voltage Leakage: The issue of "voltage leakage: was a major problem in the early days, as the "stray voltage" in the pool water tended to destroy the pool pump and pool heater internals in a short time!

Oh ... and the danger to pool users if they "shorted" to earth while in the pool (i.e. don't grab anything "Earthed" outside of the pool - such as a stainless steel pool ladder while standing in the pool)!

Swimmers with PaceMakers (Heart monitors) were deemed to be at risk, according to one medical advisor, but I have had no negative feedback on the accuracy of this warning.

Cascade circumvented the voltage leakage problem to a large degree by installing an earth strap from the pool ladder to an earthing rod.

In later years, as stainless steel pool ladders went out of fashion in favour of internal "walk in" steps, we started installing bi-metal earth plate internally in the pool skimmer connected to an earth wire and earthed to the steel pool frame.

Cascade continues this practise to this day - even though we don't generally fit saline chlorinators to our pools any more - in favour of passive Ozone - we include the earth strap wire in case our customer retrofits a "Salty" at some later stage! We don't want our pools to constitute a hazard even if we were not directly responsible!

My 'Salt Chlorinator' idea was taken to the USA in 1973:

I took two UL approved sample units to the U.S.A. (1973 Chicago Trade Fair (?) Illinois, USA) where great interest was shown in them - in fact so "popular" that my two sample IG450s both 'went missing' on that trip -

The following year I returned to the Annual Pool Show - only to see a proliferation of similar units to the IG450 - even ones painted bright Yellow like ours were - being manufactured in such diverse places as South Africa, Mexico and Australia.

SUMMARY:
In the period 1965 to 1971, I had spent nearly 6 years involved in the residential swimming pool industry in the USA, United Kingdom and Europe, and had never seen any pool device like a Salt Chlorinator available on these markets during this time.

I have been unable to find evidence of any use of such a device prior to my development in the 1960's or my introduction onto the market of the IG450 in the early 1970's - although I have heard anecdotal stories of similar developments in Australia around that time, but nothing that was on the home or overseas pool industry market - so I must assume that in 1972 'Larry Ogden and Cascade Pools New Zealand' were the first commercial provider of residential Salt Water Pools Chlorinators.

In 1972 I had investigated obtaining a World Patent, but the cost (quoted at $US 33,000 - the $NZ was par value at that time). This cost was far too much for a youngish 31 year old to come up with - especially as I had recently purchased a three-bedroom house on a half-acre in a nice Auckland suburb for $NZ 16,500. 

After I saw similarities to my Chlorinemaker IG450 from Mexico, the US and other countries on the US market I subsequently learned from the Patent Attorneys that the World Patent would have meant fighting a Patent case personally in each of the countries that were making similar devices - so it would have been beyond my resources to do so!

When I asked the Patent Attorney why they didn't bother to advise me of this detail previously, when I was considering trying to raise the $33,000, their response was ...

"You want Legal Advice? We are the Patent Office... Legal is the next door on the right down the corridor"
- but I guess that's lawyers for you!

Why don't we use saline chlorinators today?

In our opinion our combined Aquagenie+Ozone system is far better, cheaper to operate and more reliable at sterilising pathogens & bacteria in the swimming pool -making your pool safer for your children.

And after all - isn't that the whole idea?


 

Without Prejudice E&OE (C) 2002
Updated Revised and Checked for veracity August 2022