SWG & Chemical Automation Systems

[Zephyros]

Greetings all, I'm a short time member reading all I can to learn how to take care of the pool & spa that came with the house we bought in Southern California. The pool & spa were built in 1990, the pool is a 14x30" Freeform Gunite and the spa is 8' dia.

My wife has Eczema and cannot swim in a chlorine pool so I'm hoping that installing a SWG system and Automated Monitoring would allow me to more tightly control the water balance so my wife would be able to enjoy the pool & spa.

I've read all the pros and cons about the many brands and was thinking about the AutoPilot Total Control, SWG, ORP & PH monitoring, along with the Stenner Acid Tank System for PH Control. But I read Jason's cautions about how ORP can be erratic in a SWG pool so it may be better to just turn it off or go with a Free Chlorine Sensor. So I went searching for FC / PH Controllers and was only able to find the Chemtrol and Poolwarden that looked suitable for residential use.

However, as I looked into using free chlorine sensors in an outdoor SWG pool I was told they don't work with CYA as it combines with the free chlorine so there so there is no FC to measure. Perhaps I'm missing something or do I have it correct?

Any ideas or comments would be greatly appreciated, suggestions of equipment brands or models would be helpful as well. For example, maybe I should just go with the AutoPilot Digital and the Pentair SmartPH system?

Best Regards, Tom

 

[Poolsean]

Hi Tom,

Hopefully I can shed some light.
Most people experience reactions from Chloramines (combined chlorine), which is the used up chlorine, and not to Free Available Chlorine (the good stuff that kills germs and other nasties in the water).
After all, a Salt Chlorine Generator system is making chlorine. The main difference is that the Salt system is able to control and virtually eliminate the chloramines much better than normal pool maintenance methods. No Chloramines, no reactions.

The Total Control is the right direction. There are many influences that can affect the ORP sensor readings. However, you can still operate the system without the full automation of the sensors. Just don't order the 75001, Pool Chemistry Controller Box (for the ORP and pH sensors).
This pH Control alternative would included the following:
75003, Digital for the Total Control
75005, 15 Gallon Tank with Stenner 45M-1 chemical feed pump
941XX, with 05, 07, or 13, representing the XX part of the part number, which reflects the cell size.
In this mode, you adjust the Purifier % setting to maintain your desired chlorine level. This is manually controlled, but with the Automatic Temperature Compensation feature.
You also adjust an Acid Dosage Rate, xx amount per hour, per day, or per week to maintain your desired pH level. This too is manually controlled.
This will require an initial testing and adjusting to dial in your system to the demands of your pool.
MOST residential pools can operate this way just fine. I would recommend the ORP and pH sensors for smaller pools, indoor pools, and covered pools.
Once the % for Purifier and Acid Dosages are fine tuned, very little is needed maintain your pool to optimum efficiency.

Cyanuric acid can still be used for outdoor pools with ORP controllers, but must be maintained below 50 ppm. 30 - 50 ppm is the prefered range to maintain.

Hope this helps.

 

[JasonLion]

Simple percentage based automation of a SWG is nearly perfect in an outdoor residential pool, so there really isn't any need to look for something fancier than that. Having PH automation can be very nice, and the PH automation does work well. The only negative to PH automation is the cost.

 

[Zephyros]

Hi Jason and Sean,
Thanks so much for the information. I have a few follow-up questions please.

Sean, I understand I could do the manual % adjust on the SWG and the manual adjust on the Stenner pump, but frankly I'm looking for automation to minimize my time required to maintain the pool, that’s why I’m willing to pay a few bucks for the benefit, if I go with the Total Control, I like that automated capability.

You mentioned ORP may be okay for a small outdoor pool. My pool & spa are about 11,000 gallons. I’m in Southern California at 1800 feet elevation. We get some fairly regular breezes so there is a small amount of the normal stuff that gets blown into the pool, nothing to much out of the ordinary. Do you think the ORP would behave in my situation (please let me know if you need any other details)?

From the rule about oversizing the Salt Cell for improved longevity, do you think the RC-42 is more than adequate for my 11,000 gallon pool, or should I just step up to the RC-52? (I like the idea to be able to crank it up if you want to shock the pool.)

Jason, regarding "Simple percentage based automation of a SWG is nearly perfect in an outdoor residential pool" Are you saying with a few simple setup tests (I'm going to order the TF Test Kit) I can set-it and forget-it, well maybe I could retest every week or two (yes I'm looking for the lazy way out)?

Or, depending on automation, I'm still intrigued by the free chlorine sensors, could you please explain more about these, why you like them and what brands you think are good to look at for residential use? These are the two I've found:
http://www.sbcontrol.com/ch255.htm
http://www.controlomatic.com/poolwarden.html

I thought maybe I could use one of these for my Chemical Sensor System and them buy the AutoPilot SWG and Stenner Tank to dose the pool, based on command from those? (again, I’m getting a little complex and expensive but to me it may be worth it.)

Best Regards, Tom

 

[JasonLion]

If you love complicated technical gadgets then you want ORP control. If you want to reduce the amount of work/thought you put into your pool then avoid ORP. ORP is finicky and requires some knowledge and some luck to get working. Simple percentage based automation is nearly perfect in an outdoor residential pool, especially with the AutoPilot temperature compensation feature. I adjust mine about two or three times a year max.

After the initial setup testing once a week will work well. With PH automation, and once you get more familiar with the pool you can probably test even less than that.

I would not go larger than the RC-42 cell with a 11,000 gallon pool. When the normal setting is so low you lose resolution and need to make large steps, which is wasteful. Also, the cell life gets to be so long that chances are it will break for some other reason before the cell wears out, eliminating the financial advantage of getting a larger cell.

The existing free chlorine sensors have been having problems with the membrane getting clogged when there is CYA and/or salt in the water. They are also rather expensive. If you do find one that works, and it has a relay to control a chlorine feed system, you could rig it up to control a regular AutoPilot Digital system. Chemtrol has a new sensor design that is supposed to solve the clogging problems, but it hasn't been around very long so I haven't heard how well it works yet.

Adding bleeding edge technology, like the PPM chlorine sensor almost always makes the system take significantly more work to maintain than it would with a simpler approach. Which brings us back to the question of how much you like playing around with tech, vs being serious about having the pool be simple to maintain. Simpler systems are simpler to maintain. Fancier automation is fun to play with, but doesn't usually end up reducing the amount of work you need to do.

 

[Zephyros]

Hi Jason and Sean,
Jason, thanks for the wise advice, I've decided to go with your simple approach, without the sensors. I liked the advice so much I joined as a Lifetime Member and purchased the TFT Test Kit.
With my 11,000 gallon pool, I was looking at the specs of the RC-35 cell vs. the RC-42 cell, it looks like the RC-42 cell output is about 22% greater than the RC-35. However, the RC-35 lists itself for up to a 35K gallon pool, while the RC-42 lists itself for up to a 42K gallon pool. I don't mind spending the extra money for the RC-42 but I want to make sure I size properly. Your concern about going to large due to the lost resolution, is the RC-42 to large for my 11K gallon pool and should I just stay with the RC-35?

Sean, based on one of your other posts, I think this is the equipment I need, could you please confirm this?
Autopilot SWG & PH System
#75003 Autopilot Digital Unit
#75005: PH Acid Feed System (220v - 60 Hz Stenner Tank & Pump)
#75008: Acid Pump Auxiliary Relay Kit
and either of these two cells:
#94105: Manifold with RC-35 Cell (35,000 gallons/127m3) (1.28 lbs/day (0.58 kg/day)
#94107: Manifold with RC-42 Cell (42,000 gallons/155m3) (1.56 lbs/day (0.71 kg/day)

Best Regards, Tom

 

[JasonLion]

My normal rule of thumb is that the ideal SWG size is between two and three times the actual size of the pool, perhaps a little larger in areas with extreme amounts of sunlight and high temperatures (think Nevada). Larger or smaller than that will work, just not be ideal.

 

[Poolsean]

The 75008 is only needed if you're going to use the 75003 to control your circulation pump. Otherwise, the rest is correct. The RC-35 cell is large enough to take care of your pool.
I still recommend getting the largest size cell you can afford though.