The scariest water I have ever seen in my life!

[PoolDoc]

What I see in talking to builders, at the SCP counter in Chattanooga, and over the years in various places, is that most builders HATE pool chemistry, and know very little about it. I have no doubt that the builder believed that the Pool Pilot would do just what he told the owner. I'd bet, if you did up the PP literature, you'd find that that's just what it claims, until you get to the really fine print

As you know, one of my pet peeves is 'automation' systems that use pH or ORP electrodes to 'sense' the pool water. The problem is simply that calibration MUST be maintained or they WILL drift off. I don't know about the Pool Pilot, but I know that with the mainline commercial controllers (Strantrol, Chemtrol, K & E, etc), this little fact is NOT part of the sales pitch. Some, like K & E will tell you after the fact. Others, like Strantrol will tell you that you really, really need their bi-annual calibration service (at $150 & up per service call) but not explain why.

I've seen multiple serious episodes resulting from 'trusting' uncalibrated controllers, including gradual swimsuit destruction on an entire swim team; rapid swimsuit destruction on a water aerobics instructor turning it into a virtual 'thong' in one 3 hour session of back-to-back classes; up to the literal destruction of a facility's stainless steel ductwork and gutter system as well as their heaters and the heat exchanger on the air handler. In the last case, damage exceeded $100,000 over a single weekend.

I'm not really a fan of pool automation. Although I haven't seen some of the things that have been released in the last 3 or 4 years, the stuff I have seen almost inevitably becomes a problem. And chemical automation, by its dependence on 50+ year old electrode technology, inevitably leads to problems.

In-floor vacuum system, automatic covers, colored pool lights (the new LED ones may be OK), remote control systems, computer control systems, chemical control systems -- you name it, and I've seen them go from 'new' to 'broken' in months, weeks or even days!

The only reliable 'automation' I've seen is electromechanical time clocks!

Ben
"PoolDoc"

PS: Yes, I know that some of those things will work well if "maintained properly". I've used, and preferred, digital time clocks to the electromechanical ones. But, I was never successful at training any on-site staff to set those clocks. Even the automation that 'works', often won't work long with the staff available on site, whether it's a lifeguard or a pool manager or "Mom". I've argued for years that pools should be designed to be operated successfully by the staff that's available, rather than the staff that 'should' be available!

[Poolsean]

"I'd bet, if you did up the PP literature, you'd find that that's just what it claims, until you get to the really fine print"
You'll find the Pool Pilot lit says that the pH is near neutral but in no way do we claim that it will drive up the pH and that constant acid additions are needed. In fact you'll find that in my responses that I'm fairly suprised at some of the swg pool owners that use MORE acid than in a bleach pool.

[waterbear]

"I'd bet, if you did up the PP literature, you'd find that that's just what it claims, until you get to the really fine print"
You'll find the Pool Pilot lit says that the pH is near neutral but in no way do we claim that it will drive up the pH and that constant acid additions are needed. In fact you'll find that in my responses that I'm fairly suprised at some of the swg pool owners that use MORE acid than in a bleach pool.

Sean,
Correct me if I'm wrong here but the electrolytic generation of chlorine from salt water produces sodium hydroxide as a byproduct. The 'offline' units of the past had a separate tank for the waste lye to prevent the pH rise but the modern inline units like the PoolPilot (and the Aqualogic on my pool) do not and the sodium hydroxide is discharged into the water. I don't know if the concentration generated is higher than the amount found in the same amount of liquid sodium hypochorite needed to maintain the same FC level or not. I do know that my 6600 gal fiberglass pool does need acid about ever 3 weeks (about a pint and a half to two pints) to bring my pH down from about 7.7 back to about 7.4. I have never chlorinated this pool any other way than the SWG so I don't have anything to compare it to but SWGs DO cause the pH of a pool to rise! There is not way to get around the chemistry involved!

I have noticed that among my customers with SWGs the ones that are running lower CYA levels (and therefore higher cell outputs to maintain the chlorine) do seem to go through more acid and have more problems keeping the pH in line and new plaster pools with SWGs seem to go through a LOT of acid (then again, many new pools on trichlor do also!)

[Poolsean]

Although you've got the high pH of the Sodium hydroxide, you also have the low pH of chlorine gas (which instantaneously converts to 100% pure sodium hypochlorite - without the high pH nature) to keep it fairly neutral.
We typically say that if you just leave the pH alone for awhile, it will climb to about 7.8 - 8.0 and hover around there, and not much higher.

The Unichlor systems of old (the one you're describing with the waste Lye tank), were modified in the late 80's to reintroduce the lye as a pH balancer. They called this the diluter kit. Again, one side produced chlorine gas that was syphoned into the return line, whereas the caustic side was commonly drained, but then was used to return some sodium hydroxide back into the water, thereby increasing the pH back up from the low pH effects of the chlorine gas.

[waterbear]

Although you've got the high pH of the Sodium hydroxide, you also have the low pH of chlorine gas (which instantaneously converts to 100% pure sodium hypochlorite - without the high pH nature) to keep it fairly neutral.
We typically say that if you just leave the pH alone for awhile, it will climb to about 7.8 - 8.0 and hover around there, and not much higher.
Yep, my pH goes up to about 8.0 and stays if I don't add any acid.
The Unichlor systems of old (the one you're describing with the waste Lye tank), were modified in the late 80's to reintroduce the lye as a pH balancer. They called this the diluter kit. Again, one side produced chlorine gas that was syphoned into the return line, whereas the caustic side was commonly drained, but then was used to return some sodium hydroxide back into the water, thereby increasing the pH back up from the low pH effects of the chlorine gas.

thanks for the info!

[PatL34]

"I'd bet, if you did up the PP literature, you'd find that that's just what it claims, until you get to the really fine print"
You'll find the Pool Pilot lit says that the pH is near neutral but in no way do we claim that it will drive up the pH and that constant acid additions are needed. In fact you'll find that in my responses that I'm fairly suprised at some of the swg pool owners that use MORE acid than in a bleach pool.

Sean,

Agree with most of what you say here, except for the final sentence.

In fact you'll find that in my responses that I'm fairly suprised at some of the swg pool owners that use MORE acid than in a bleach pool.

There two reasons for using more acid than in a bleach pool.

1. The acid replaces the bleach component of the bleach pool.

2. A gunite/plaster pool will also use more because of the leaching from the walls.

Liner pools appear to use little acid, but still need it.

Pat