I converted my traditional chlorine pool to a SWG (Intellichlor IC60) pool about a week ago. I have an older, 38,000 gallon inground pool. The FAC levels are about at 2, total chlorine is normal as well. I have a Cat 2000 controller and the ORP levels are very low, like 125. What is the best way to manage this and am I missing something with keeping the ORP levels up with a Pentair IC60 SWG unit?
Intellichlor SWG and Orp levels
- Thread starter ronaldo0501
- Start date
Ron,
Not too many of us here are fans of the ORP system, as to use it your CYA has to be very low... With a saltwater pool we recommend a CYA of about 70 and an FC of 5 or 6 ppm..
See the saltwater section of this chart.. FC/CYA Levels
Let's see if we can get an ORP user to chime in..
Thanks,
Jim R.
Not too many of us here are fans of the ORP system, as to use it your CYA has to be very low... With a saltwater pool we recommend a CYA of about 70 and an FC of 5 or 6 ppm..
See the saltwater section of this chart.. FC/CYA Levels
Let's see if we can get an ORP user to chime in..
Thanks,
Jim R.
I've been running an intellichem system with an IC-40 for about 9 months now and establishing a reliable relationship between FC and ORP has been an ongoing battle. WHEN STABLE I typically see an ORP of around 620 at night and 580 in full sun. The FC will be around 6-7PPM. This is with a CYA level of 30.
But here's the rub, ORP is so sensitive to other things. pH for example - if you're not controlling pH to +/- .1 max, your ORP will vary so much with pH you'll never correlate it to FC. I can see when my intellichem injects acid into the pool. ORP will rise as pH drops from about 7.55 to 7.45.
There areother redox couples in pool water besides just the HOCL/CL. The ORP sensor can only measure the total redox state.
The H2/H+ redox couple is a big problem. The IC-40 makes H2 during its operation. A small amount of this H2 dissolves in the water, very small, but it turns out even a very small amount of dissolved H2 in water lowers ORP a lot. So in my pool the harder I drive the IC-40, the more hydrogen generation and the ORP can actually go down into the 400s. I'd still love to know why my pool seems so sensitive to this where others do not report this phenomenon so much. When I turn of the IC-40, ORP will RISE significantly over the next few hours.
I've had to find the right duty cycle for the cell in order to balance enough FC generation without overproducing H2. This means I cannot use ORP setpoint to control FC.
All that said, I've never seen ORP as low as 125. Have you noticed ORP falling with the IC-60 on and recovering with it off? Could your probe be defective? There's no real calibration process for an ORP sensor, but cleanliness is important as any crude on the probe will either slow down the response of the probe or if it affects the local redox state, will not represent the actual pools waters ORP.
ORP isn't valueless. If you have established a stable system, a crash in ORP will tell you when something has gone askew.
But here's the rub, ORP is so sensitive to other things. pH for example - if you're not controlling pH to +/- .1 max, your ORP will vary so much with pH you'll never correlate it to FC. I can see when my intellichem injects acid into the pool. ORP will rise as pH drops from about 7.55 to 7.45.
There areother redox couples in pool water besides just the HOCL/CL. The ORP sensor can only measure the total redox state.
The H2/H+ redox couple is a big problem. The IC-40 makes H2 during its operation. A small amount of this H2 dissolves in the water, very small, but it turns out even a very small amount of dissolved H2 in water lowers ORP a lot. So in my pool the harder I drive the IC-40, the more hydrogen generation and the ORP can actually go down into the 400s. I'd still love to know why my pool seems so sensitive to this where others do not report this phenomenon so much. When I turn of the IC-40, ORP will RISE significantly over the next few hours.
I've had to find the right duty cycle for the cell in order to balance enough FC generation without overproducing H2. This means I cannot use ORP setpoint to control FC.
All that said, I've never seen ORP as low as 125. Have you noticed ORP falling with the IC-60 on and recovering with it off? Could your probe be defective? There's no real calibration process for an ORP sensor, but cleanliness is important as any crude on the probe will either slow down the response of the probe or if it affects the local redox state, will not represent the actual pools waters ORP.
ORP isn't valueless. If you have established a stable system, a crash in ORP will tell you when something has gone askew.
I had exactly this problem, I then read that SWG pool need an ORP probe with a gold electrode, I bought one of these a few days ago and since then my ORP is doing pretty much what I expect it to do and no longer drops when I turn on the SWG.
Glad that worked for you.
Ironically, a couple of months ago I replaced my gold probe from Sensorex with a new standard Pentair platinum unit. The old probe was worn out, reading ORP in the low 500s no matter what the FC. I decided to try the platinum probe again because my CYA is down to 10-15, below the limit recommended by Pentair. So far I've had good success with the new probe. Sensical readings in the 700s.
I still see ORP drop when the SWG turns on after being off for a long period though.
My platinum one used to drop pretty much as soon as I turned my SWG on, I would leave it a while thinking it would "catch up" with itself sooner or later but after waiting a while, usually too long! I would turn it off manually, my ORP reading would then shoot up shortly after, I am assuming because the hydrogen was no longer being generated and by then my chlorine was off the scale, my pool is only smallish, around 25m3 and my SWG is for pool up to 90m3 I think (Pentair SC-75) so it does not take long to generate enough chlorine for the pool.
Do you have intellichem?
If so I've found setting the ORP dosing to "by time"' rather than "to setpoint" allows me to throttle the output of my IC-40 reducing the severity of the drop effect. I have it current set for 10 minutes on and 4 minutes off. It still turns off when ORP setpoint is reached but its not jammed on 100% all the time.
I guess if your SWG is connected directly to intellicenter you can still set a percentage via the app.
Interesting discussion. My probe is platinum and I typically see ORP levels between 620 and 720. I do know that the FC will always be at 3 when it is 620 and 6 when it is at 720 and that is just how my system works. My system is not IntelliChem, rather it uses Atlas Scientific industrial probes for pH and ORP but the concepts are identical. I do not see ORP drive in any direction from my IC40 which on my 36kgal pool which runs quite hard to keep up. So I don't have the issues you are referring to.
I wonder though if there is perhaps some polarization that might be occurring from the cell electrolysis. I saw one other person with a similar issue as yours and could not quite put a finger on it. As soon as the cell engaged the ORP would drive south. He described it as an inverted relationship with ORP. Then when the cell turned off it would creep back up slowly. This made the ability to use demand based chlorinator dosing impossible. The circuits for pH and ORP as well as EC non-carbon probes are typically isolated so I wonder if there is some probe polarization that occurs as a result of the electrolysis from the cell.
The fish tank guys deal with ground potential, loop, and polarization issues all over their forums while describing similar ORP anomalies. I guess if you are killing off your pets you might push pretty hard for solutions since out of range ORP produces floaters. They do often use gold probes because platinum is typically better rated only if the ORP is > 500mV, but I think all of that that might just be coincidental. Pools aren't industrial sanitation processes and they aren't fish tanks either so the ranges for probe materials might not be that critical. For them inductors like heaters and submersible pumps on the same circuits as the probe amplifiers seem introduce the interference and the solution is often to equalize the ground potential issues.
Just curious, do either of you guys have the power center bonded or not. Not sure which end I am typing out of but perhaps the fishy folks have at least pointed at potential solutions.
I wonder though if there is perhaps some polarization that might be occurring from the cell electrolysis. I saw one other person with a similar issue as yours and could not quite put a finger on it. As soon as the cell engaged the ORP would drive south. He described it as an inverted relationship with ORP. Then when the cell turned off it would creep back up slowly. This made the ability to use demand based chlorinator dosing impossible. The circuits for pH and ORP as well as EC non-carbon probes are typically isolated so I wonder if there is some probe polarization that occurs as a result of the electrolysis from the cell.
The fish tank guys deal with ground potential, loop, and polarization issues all over their forums while describing similar ORP anomalies. I guess if you are killing off your pets you might push pretty hard for solutions since out of range ORP produces floaters. They do often use gold probes because platinum is typically better rated only if the ORP is > 500mV, but I think all of that that might just be coincidental. Pools aren't industrial sanitation processes and they aren't fish tanks either so the ranges for probe materials might not be that critical. For them inductors like heaters and submersible pumps on the same circuits as the probe amplifiers seem introduce the interference and the solution is often to equalize the ground potential issues.
Just curious, do either of you guys have the power center bonded or not. Not sure which end I am typing out of but perhaps the fishy folks have at least pointed at potential solutions.
I wrote my own controller which uses ORP & PH probes, the PH is injected in using a peristaltic pump and the controller also controls my pump speed, I set the on\off points at a certain ORP level which can be different for on and off, the SWG has 3 power settings which I have been playing around with, so when the controller goes down to its "on" point it then stays on until its "off" setting, if I have the SWG on the lowest level it will be producing chlorine for 33% of the on time, at the moment I have it on 100% of the on time which is controlled by the controller.
The controller is built on a raspberry pi with the probe circuits coming from Atlas Scientific and the pump and PH pump just being controlled by relay boards attached to the raspberry pi. So I could do something similar to your 10 on & 4 off by setting the SWG to level 2 probably.
Yes I am running similar equipment. Here is a writeup on the controller we built.
github.com
DIY REM Chem Controller
An application to control pool equipment from various manufacturers. - tagyoureit/nodejs-poolController
github.com
Looks much more technical than mineYes I am running similar equipment. Here is a writeup on the controller we built.
DIY REM Chem Controller
An application to control pool equipment from various manufacturers. - tagyoureit/nodejs-poolController
I am not a software engineer (I was a network engineer actually) but I have been around IT systems for quite some time, mine just started out as something I could reach remotely as I rent my place out for the summer and was just something I accessed and updated using CLI but then it grew with the addition of web pages to control it, just using PHP and HTML, and then added pump control, refined the way it work many times, added safety features to limit acid dosing as with yours, all mine really does is run round a big loop checking the values, I average out the last 20 values to allow for the odd erroneous reading, PH is read continually but acid only added every hour (adjustable for longer or shorter times) to allow for the last lot to have circulated and a flow switch to make sure that there is water flow before doing anything. It turns an electronic relay on for the SWG, mainly wrote it as the ones I saw in my budget were pretty basic and I couldn't find anything remotely accessible, I am sure the high end systems would be but they would probably cost more than my pool was originally!Just read a bit more about yours, good write up btw and quite a few similarities with mine, I used the dallas temp probe directly into the rpi to save some money and also have a LCD readout on the unit with a few buttons on for basic pump controls so the pool guy that I have to have when my place is rented out can stop\start\run on full speed the pump without needing full access, keep meaning to do a bit of a write up on it but not got round to it yet, seems to do all it needs to though although still give it the odd tweak when needed, mine is written in python with web pages in html\php which I could just about get my head round with a lot of googling!!
and also have a LCD readout on the unit with a few buttons on for basic pump controls so the pool guy that I have to have when my place is rented out can stop\start\run on full speed the pump without needing full access, keep meaning to do a bit of a write up on it but not got round to it yet, seems to do all it needs to though although still give it the odd tweak when needed, mine is written in python with web pages in html\php which I could just about get my head round with a lot of googling!!The REM platform supports the 1-wire temp sensors as well but the industrial pH probes have a built in PT1000 that I tapped for temp compensation. There are a number of folks that are using either an ADC fed temp sensor or the 1-Wire DBS sensors for that if they use the lab grade probes. The entire platform is written in nodejs and TypeScript. At the pad I have a 10 inch LCD mounted to the dead panel that allows access to all the functions of the pool and the entire thing can be accessed from a browser. For the most part I don't have a need for a cut down interface since it is always accessed by me.
I read much more often than you, in the neighborhood of every few seconds and apply a 5 median sample for smoothing. I don't see any spikes with that, probably because all of the readings off the probes are capacitive differential readings to start with. I'd love to see your writeup if you get around to it.
I use IntelliCenter but the overall controller can communicate with a variety of RS485 equipment, pumps, relays, heaters, valves... etc. These can be used to expand an existing system or start from scratch with a pile of equipment.
I read much more often than you, in the neighborhood of every few seconds and apply a 5 median sample for smoothing. I don't see any spikes with that, probably because all of the readings off the probes are capacitive differential readings to start with. I'd love to see your writeup if you get around to it.
I use IntelliCenter but the overall controller can communicate with a variety of RS485 equipment, pumps, relays, heaters, valves... etc. These can be used to expand an existing system or start from scratch with a pile of equipment.
As I said, yours is way more advanced than mine, nice piece of work from what I can see, I do actually read every few seconds and the ORP\SWG works in real time it is just the PH controller that only uses the reading every hour although it is also taking a reading every few seconds and if there are any anomalies sends me an email, I don't have chlorine dosing built in, although I don't think it would be a major problem to add, as I built mine purely for my setup with the SWG.
One reason I built it is that I have a retractable pool shelter on my pool so that if I just had the SWG on a timer and the pool was not used for a while I think the chlorine would build up to a high level so I needed some sort of controller to allow for this and I also wanted remote access to keep an eye on it when I was away, yours looks like a much more professional piece of kit than mine!
I also send my readings to ADAfruit as an easy way to graph the readings over the past 30 days which makes it easy to keep an eye on.
I have a 4 line 20 character LCD display so not quite on a level with yours
I am newish to pools but one came with a small place we bought in France a few years ago, the controls are in a box in the ground with a hinged cover, just had a filter and pump when I inherited it but have been upgrading ever since to make it a bit more user friendly, added a heat pump first, then variable speed pump, then last year the SWG which gave me the need for the controller then added the shelter this year so now have quite a few things shoehorned into the equipment box but I think I am about where I want to be, the company who look after the pool when it is rented out reckon it is one of their smallest pools but also one of the most technical! (it is about 7mx3m)
One reason I built it is that I have a retractable pool shelter on my pool so that if I just had the SWG on a timer and the pool was not used for a while I think the chlorine would build up to a high level so I needed some sort of controller to allow for this and I also wanted remote access to keep an eye on it when I was away, yours looks like a much more professional piece of kit than mine!
I also send my readings to ADAfruit as an easy way to graph the readings over the past 30 days which makes it easy to keep an eye on.
I have a 4 line 20 character LCD display so not quite on a level with yours
I am newish to pools but one came with a small place we bought in France a few years ago, the controls are in a box in the ground with a hinged cover, just had a filter and pump when I inherited it but have been upgrading ever since to make it a bit more user friendly, added a heat pump first, then variable speed pump, then last year the SWG which gave me the need for the controller then added the shelter this year so now have quite a few things shoehorned into the equipment box but I think I am about where I want to be, the company who look after the pool when it is rented out reckon it is one of their smallest pools but also one of the most technical! (it is about 7mx3m)
If you have any RS485 controlled equipment there are quite few tools in there that will help you control them including VS, VF, and VSF pumps and chlorinators. If I am not mistaken that Sta-Rite chlorinator has the same innards as the IC-25 from Pentair so there is control for that too. All of the source is provided on the repo and you can install it on most platforms with a CPU and it will run in simulation mode.
It is funny though how things grow out of necessity. Heck I am about to drop moisture, soil temp, and UV sensors around all the plants in my landscape. They are going to excavate this place in a thousand years and wonder what kind of crazy facility they happened upon.
It is funny though how things grow out of necessity. Heck I am about to drop moisture, soil temp, and UV sensors around all the plants in my landscape. They are going to excavate this place in a thousand years and wonder what kind of crazy facility they happened upon.