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Hi - I am considering putting a SWG w/ Acid Injection / ORP (Like the AutoPilot Total Control) system into my new pool (not built yet), but some of the initial feedback I am getting is that people are scared of these - my pool designer in particular said he put in 6 of these types of systems (NOTE: He did not remember the brand, so I am not saying it is the AutoPilot brand - he is checking on this for me...), and it caused all kinds of problems, even corroding the stainless steel fittings in the pool.

I am very much maintenance-averse, and not opposed to spending $$ to lessen my involvement in the pool, but I also don't want to try something that is considered by many to be problematic.

Any experiences, alternatives, ideas? (My main goal here is to not have to manually add acid to the pool.)


Thanks!

-randy

I have installed several T/C systems and they are extremely reliable. They will require occasional calibration, but I have one that is 6 months old, and has yet to need any calibration. The probes may need to be cleaned 1-2X per year.

As far as corrosion, there shouldnt be any reason that the water is more corrosive due to using the t/c system. Typically Salt water pools can be more corrosive because of the increased conductivity of the water. At the salt levels that most pools run at, this is really not an issue.

Typically chemical controllers work best on pools that have frequently changing chemical demands due to bather load. In most residential pools, ORP, and pH controls are a little overkill because typically chemical adjustments are not needed all the frequently.

My experience with my salt system is that it is CONSTANTLY driving my pH up, and not by a little. I'd love to have an acid injection system with it.

Oh, and let me comment on a previous response to your vacuum question -- I think a suction vacuum is much preferable so long as you won't have much large debris in the pool. I love my Hayward Navigator about 340 days out of the year; the other two weeks are when the Santa Ana winds are emptying my neighbor's pine trees into my pool. ;-/

Mike

Since I primarily install infloor cleaning systems I do not have a great deal of knowledge with Hose driven cleaners, but i do know that pressure side cleaners are more reliable, and easier on the pool equipment in general than a suction side cleaner.

If you have a lof of debris in a suction side cleaner it could clog the pump, which in turn can damage the pump, seals and fittings going into it. If a pressure side cleaner gets full, it simply will not pick up anymore debris, but will cause no ill effects on the rest of the pool equipment. Pressure side cleaners tend to last much longer, and do a faster more efficient job of cleaning the pool than their suction side counterparts. The pressure side cleaners are however more expensive than the suction side cleaners.

I know you will find (if you look into the chemistry) that is is not your SWG which is CONSTANTLY driving your pH up. If you adjust the Total Alkalinity (TA)of your pool water to the level where it should be (for your pool water), you will find the pH becomes very stable. The pH in both my salt water pool and salt water spa has needed minor pH adjustment only two or three time in the past 12 months. The correct TA for pool water depends upon the total hardness of the water (Jock Hamilton, rest his soul). United Chemical can supply a chart for this.

The problems experienced by your pool designer can only be caused by faulty equipment or construction or by user error. pH control and acid injection is not inherently problematic - because the pH should only ever be in the correct range if the controller operates properly. Stainless steel pitting etc is more than likely caused by incorrect or non-existent bonding because 3000ppm salinity won't do it on any reasonable grade stainless.

Ross, you may recall that we discussed this ad nauseum when I first reported the problem. As I recall Bob's explanation, it seems to me that the salt generator produces NaOH (a base), ionic Chlorine and hydrogen. I'm not sure why the hydrogen doesn't balance the pH, unless maybe it's gassing off. In any event, I worked tirelessly to follow the instructions of the experts here to get my TA and then pH into the suggested ranges, and still my acid demand was upwards of a gallon a week (for a 22,000 gallon pool).

The water's too cold to calculate a proper index now, but once May rolls around we can revisit this and you can help me get it right. :-)

Mike

On 2/27/2006 8:48:29 AM, Ross Townsend wrote:

>3000ppm salinity won't do it
>on any reasonable grade
>stainless.
>


It shouldn't, but it will certainly magnify any problems there is with the bonding.

You really do not pick the proper TA to go w/ the CH of the water. Because if the CH of the water is 20, you would have to jack up the TA to compensate for it to achieve proper balance on the Hamilton index. The water wouldnt be good, but the formula would mathematically work out.

You want to get the levels into their ideal ranges then fine tune them to the ranges within the index. Hamilton's is probably one of the least used in the industry, the Langlier index is the most popular, and will more than likely continue to.

I agree, a salt pool shouldn't drive the pH up, it possible that the surface of the pool is (plaster?).

Absolutely. Measure the TH (not just 'calcium hardness') and I will tell you where your TA should be.

The Langlier index was developed way before any of us were born...

It was not developed for swimming pools, but for closed boiler systems..


Jock's was developed for swimming pools by a swimming pool person in real time.

It has been shown to be accurate...

Bill Tech II

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Bill Tech II

Hey Bill, now when I asked what the Hamilton index was, no one knew, that hurts my feelings my friend.
Keith B. Janus
Janus Mechanical Consulting

On 2/28/2006 5:00:12 PM, Bill Storm wrote:

>
>Jock's was developed for
>swimming pools by a swimming
>pool person in real time.
>
>It has been shown to be
>accurate...
>
>Bill Tech II


Since when has the langlier index been proven to be inaccurate?

IMO Most of ucc's chemicals are all bark and no bite. Some never work as advertised while others sometimes do and others, they do not. I honestly would prefer to add sugar water to a pool because its much cheaper.

The differences are so subtle between the 2, that the variance on a standard test kit will keep both index's close. The only problems I have with the hamilton is that the pH, and the fact there is no temperature compensation. The temperature of the water certainly should play a factor in whatever index is used.

pH 7.8-8.2?? That is a good way to retard your sanitizer. No health department in the country will allow you to operate w/ a pH averaging 8.0.<

When you go back and read Dr. Langlier's writings you wonder why this was ever applied to swimming pools...

People just started using this index, it has never been proven the index should be applied to swimming pools.

Sense comerical pools are only 5% of the market I am not concerned about Health departments, but they do allow pH above 8.0.

Bill Tech II

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Bill Tech II

I can only speak for Ohio and Michigan but the max is both states is 7.8pH.
Keith B. Janus
Janus Mechanical Consulting

Same w/ Washington and Oregon. If you go over 7.8 you will be shut down ( well, they may threaten it=)).

This has to do w/ how the sanitizer reacts to the pH, at 8.0 its much less effective than if it was at 7.5. Jock was a very smart man, but not always right. He once told me that a fiberglass pools never need to be shocked. I am still confused with the logic behind that one. I dont know how the surface of the pool has anything to do w/ breakpoint chlorination.