Intellichem - and yup orp issue

[dw886]

I tried to create a table of ORP readings to FC readings back in May 2017. I just took a look at my notes, and I noted "covered" or "uncovered" in my notes, but I don't think that I diligently tested it strictly kept one way. That may be part of the key, because I know that the cover does play a part in all of this.

That being said, I had a stretch last fall where ORP was staying consistent, and the pool was closed. I opened it up to water that had a haze to it, and I had to slam for 6 days. I'm wondering what Algae does to ORP values...

 

[jonpcar]

Drdram, thanks for the reply! Do you have a pointer to your diyautomation article, the link I found was dead and a search (probably with the wrong parameters), turned up nothing.

Yes, I have been reading a bunch of the literature on orp and realize what a challenge/impossibility it is to get it to work. Almost no successes for outdoor pools, maybe only yours,haha. It’s possible there are more that are not documented on the web. In any case, I will keep looking because eventually, I am determined to give it a try just to see if any sense can be made of it.

Dw866, your reply came in as I was typing this. It seems like there are possibly multiple factors that must be kept track of if there is any chance of making sense of ORP readings...you mentioned tinkering and monitoring...I love tinkering! Monitoring...not so much, especially after I’ve finished my tinkering, haha.

 

[dradam]

Below is my original article. Again, I have been succesful when as many parameters as possible remain stable-- circulation, temp cya. .
Orp is finnicky at best but can direct you when the numbers are off. Best to keep FCL a little too high than too low for algea control,.

BBB works !! that is your backup whenb the numbers go wrong.

Best wishes.

 

[dw886]

Since the weather here hasn't really been warm enough to swim, I've been using this time to create a detailed log of ORP and FC levels in my pool. I was on what I thought was a very controlled environment, since the pool has basically been covered for a month. I open it up every few days to throw in the robot, but nothing longer than like 15 minutes uncovered. Pool was always covered for at least 4 hours prior to taking any of the readings. FC was calculated using FAS-DPD from a TF-100. pH is the reading from the IntelliChem, and then vetted against a Taylor pH test kit. Correlation between ORP <--> FC were very consistent, until Monday. Since then, things have gone off the rails...



Then last evening, this happens - the ORP reading went from ~708 down to 560, and it started dosing, and dosing, and dosing, and dosing. This morning, when I caught it, my FC was at 7:


What's interesting to note is that the time where the huge ORP drop happened correlates with the time that I removed a skimmer plug (because I had a skimmer blocked off to repair a crack). At the same time I opened up the line coming from that skimmer back at the pad to permit water to come from that skimmer. Water level was a little low, so I threw the hose into the pool, and added water for about 1.5 hours. Now if the IntelliChem was simply only reading the ORP value from the new (city) water that I was adding, the ORP change may make sense. Problem is that the water was added last night, and the ORP value never recovered. 20 hours after turning the water off, my ORP is still reading about 150mv less than yesterday at the same time, which had my SWG freaking out for the last 20 hours.

All I can think of is to clean the ORP sensor. I changed the IntelliChem ORP setpoint to 560 to stop the dosing. It was previously at 700. FC will start to dissipate, and I'll need to figure out a new baseline in the 500s unless the ORP reading changes. These are the things that scare me about the IntelliChem...

 

[jonpcar]

I have read that orp is very sensitive to ph...any chance your slight rise in ph causes the orp to helter skelter? Does the Intellichem have a “maximum add level” per day parameter?

 

[dw886]

I have read that orp is very sensitive to ph...any chance your slight rise in ph causes the orp to helter skelter? Does the Intellichem have a “maximum add level” per day parameter?

I'm not sure if it's related to the pH, but it doesn't look so. pH has come down - currently at 7.63, and ORP has dropped to 518. Pool cover has been closed since Wednesday, pump runs 24x7 on low.

As for the maximum amount per day, yes, that does exist in the intellichem settings, and I do have it limit - can't remember exactly what though. The problem usually happens if I don't catch it quick enough - I generally test every 3 days or so, and in 3 days an IC60 can increase FC a lot on a covered pool.

 

[dw886]

So I cleaned my ORP sensor, and tested my FC. Pre-cleaning, ORP was reading 518. Post-cleaning, it's reading 501. FC is currently at 7, and pH is at 7.62. To me, it's unexplainable, unless there's some kind of an equipment malfunction...

 

[jonpcar]

Weird...your numbers looked so good and correlated nicely before that cliff. I think you mentioned your orp probe is pretty old...is it just possible that the probe just happened to fail during this “experiment”? No chance the orp probe was dry during your skimmer fix/change. I really do want to tinker with orp at some point but it seems that everyone who does runs into a similar snag...hope you can find the problem...did you try cntrl-alt-delete (reboot, haha)?

 

[dw886]

...No chance the orp probe was dry during your skimmer fix/change...

No, the pump has been running 24x7 since we started back in April. For the skimmer fix, I had just turned off one skimmer suction line - the pool was still pulling from the main drains and the other skimmer. The lines for the intellichem are fed from the main lines that run through the filter, heater, then swg,and return back to the pool.

...did you try cntrl-alt-delete (reboot, haha)?

I haven't rebooted the intellichem, but that's probably a good idea.

Weird...your numbers looked so good and correlated nicely before that cliff. I think you mentioned your orp probe is pretty old...is it just possible that the probe just happened to fail during this “experiment”? ...

ORP probe was replaced in June 2018, basically because the same sort of thing happened where it no longer correlated. I still have the old probe, and it's been store in the water-cap, so it may be interesting to swap them and see if it changes things...or maybe just order a new one...

Results have definitely shifted downwards and stayed there:

 

[Bmwtown]

No, the pump has been running 24x7 since we started back in April. For the skimmer fix, I had just turned off one skimmer suction line - the pool was still pulling from the main drains and the other skimmer. The lines for the intellichem are fed from the main lines that run through the filter, heater, then swg,and return back to the pool.

I haven't rebooted the intellichem, but that's probably a good idea.

ORP probe was replaced in June 2018, basically because the same sort of thing happened where it no longer correlated. I still have the old probe, and it's been store in the water-cap, so it may be interesting to swap them and see if it changes things...or maybe just order a new one...

Results have definitely shifted downwards and stayed there:
View attachment 103447

I will also reach out to Pentair but do you know if the Intellichem would be able to use a FC probe and not an ORP and function?

 

[dw886]

Sharing this for anyone interested, or for anyone that can explain this. This is where I really struggle to trust this. Our pool is covered whenever it's not being used, which is 99% of the time. Last week, it statistically was open about 7% (12 hours out of 168).

So earlier in this thread, I explained that my ORP had suddenly "dropped" from being consistently in the 700s down to the 400s-500s. Well, over the course of the weekend, the entire time the pool was covered, it slowly increased by 200 mV while FC has remained relatively stable. You can see that it hasn't dosed with the SWG since Wednesday, however there's 2 Trichlor pucks in the skimmers as I needed a little bump in CYA. The pool was open for about 10 hours on Monday, and 2 hours on Friday. The rest of the week, it was covered. No idea why, but now it shows 720 with a FC reading of 4, which is actually believable...



Here's the updated table with more data:


A "bump" like this in the past is precisely what caused me to have an algae outbreak, as the ORP reading was suddenly much higher than where the IntelliChem was set to dose (I had it at 410 yesterday, and moved it to 710 today). Had I not caught this, eventually my FC would have been depleted, and when I hit 0 FC, I'd start getting clouding...If I get another sudden drop, I'll have my dose level set too high, and I'll end up with way too much FC...

 

[jonpcar]

Derek, thanks for posting...I have no clue what is going on but I am very interested in ORP for the future...I'm not sure exactly why but I really want to try it sometime, haha. Keep us informed, I like all the data you are taking but there is no obvious explanation. Glad your ORP probe doesn't need to be replaced! Hopefully it will continue to operate as before. A lot of projects I have looked at have installed ORP, but there is really no followup so I suspect that it didn't work for them.

Are you still trying to keep your CYA just below 30?

 

[dw886]

Derek, thanks for posting...I have no clue what is going on but I am very interested in ORP for the future...I'm not sure exactly why but I really want to try it sometime, haha. Keep us informed, I like all the data you are taking but there is no obvious explanation. Glad your ORP probe doesn't need to be replaced! Hopefully it will continue to operate as before. A lot of projects I have looked at have installed ORP, but there is really no followup so I suspect that it didn't work for them.

Are you still trying to keep your CYA just below 30?

Correct, still trying to hold CYA at ~ 30 ppm.

I have had an additional ORP probe on order for about 3 weeks now - back from when ORP values were in the 400's, I didn't have much for choices, as the IntelliChem has a low limit of 400. So if it's reading 390ppm, the Intellichem will just keep dosing, and dosing, and dosing trying to hit 400 mV. There's no way to set it to a value of less than 400...

 

[Bmwtown]

Correct, still trying to hold CYA at ~ 30 ppm.

I have had an additional ORP probe on order for about 3 weeks now - back from when ORP values were in the 400's, I didn't have much for choices, as the IntelliChem has a low limit of 400. So if it's reading 390ppm, the Intellichem will just keep dosing, and dosing, and dosing trying to hit 400 mV. There's no way to set it to a value of less than 400...

This is making me think that I don't want to install this unit and just go with there standalone PH unit

 

[dw886]

This is making me think that I don't want to install this unit and just go with there standalone PH unit

The ORP function is finicky. I went down this path after reading all of the threads that said it was finicky, with the mindset that there must be a way to do it if you keep everything perfect enough. That hasn't proven to be the case. I'm very type A, and I've kept everything as close to a controlled experiment as I can, and a 200mV change in ORP values makes no sense...

On the pH side, how the IntelliChem manages pH versus on the IntelliPH manage pH are totally different. The intellichem has a pH sensor that senses pH changes, and then doses when it needs to. the IntelliPH unit has no sensor, and simply dispenses acid on a timed schedule. I know that for my setup, the scheduled dosing wouldn't work as well as the IntelliChem does, because the acid demand on my pool doesn't correlate to any specific timing...

To give you an idea of what I'm talking about, here's about a 1-month history of my system. The acid dosing is the blue marks inside the red box. You can see that there's weeks where it hasn't dispensed any acid at all...and then there's days where it dispenses quite regularly if the pool is being used and the slide is on... I drew in a few events at the top in case anyone is interested in the graph, and was trying to understand the timeline of events...

 

[jonpcar]

The ORP function is finicky. I went down this path after reading all of the threads that said it was finicky, with the mindset that there must be a way to do it if you keep everything perfect enough.

That's exactly what I keep thinking, and why I want to try it, though that wouldn't be for quite some time (next year). BUT, I really like your running narrative and it may dissuade me, haha. It sounds like you keep CYA fairly constant, can you think of any other factors that may impact it?: water temperature, TA...i'm scraping...

 

[dw886]

That's exactly what I keep thinking, and why I want to try it, though that wouldn't be for quite some time (next year). BUT, I really like your running narrative and it may dissuade me, haha. It sounds like you keep CYA fairly constant, can you think of any other factors that may impact it?: water temperature, TA...i'm scraping...

The funny (maybe not funny?) thing about the ORP system is that if you can "catch" the swings, and reset your setpoint before it overchlorinates (or you're left with zero FC causing an outbreak), it'll hold it's value for weeks / months and self-maintain.

To me, the biggest problem is that I want to "detect" the sudden swing so I can test / reset my baseline and adjust the ORP setpoint. If I knew that today, 710 mV ORP is ~ 3FC, and tomorrow, the ORP sensor was going to randomly re-establish a baseline at 500 mV for ~ 3FC, I could make the change. I want an alert if ORP value moves by over 50 mV in either direction in a 24 hour period of time....that would probably be enough to make me comfortable...

To answer the other questions, yes, CYA is low and constant. TA/CH never change. pH is maintained by the IntelliChem and tested regularly. Pool is covered 99.9% of the time with the autocover, and the temperature never swings more than 2 degrees. I made sure all of these were as consistent as possible when I started my logging at the beginning of the year, so I was actually heating the pool when I knew it wasn't being used for a period of time just for the sake of trying to get consistent results with my logging and testing...

I love the pH functions of the IntelliChem. I love the ORP functions when it works, but when it inexplicably swings like shown in my charts, it makes me bang my head against the wall. New ORP sensor inbound tomorrow...not sure if I should change it now though since having an ORP reading ~ 710 mV is reasonable and within the range of where it should be given my FC level...

 

[Bmwtown]

The ORP function is finicky. I went down this path after reading all of the threads that said it was finicky, with the mindset that there must be a way to do it if you keep everything perfect enough. That hasn't proven to be the case. I'm very type A, and I've kept everything as close to a controlled experiment as I can, and a 200mV change in ORP values makes no sense...

On the pH side, how the IntelliChem manages pH versus on the IntelliPH manage pH are totally different. The intellichem has a pH sensor that senses pH changes, and then doses when it needs to. the IntelliPH unit has no sensor, and simply dispenses acid on a timed schedule. I know that for my setup, the scheduled dosing wouldn't work as well as the IntelliChem does, because the acid demand on my pool doesn't correlate to any specific timing...

To give you an idea of what I'm talking about, here's about a 1-month history of my system. The acid dosing is the blue marks inside the red box. You can see that there's weeks where it hasn't dispensed any acid at all...and then there's days where it dispenses quite regularly if the pool is being used and the slide is on... I drew in a few events at the top in case anyone is interested in the graph, and was trying to understand the timeline of events...

View attachment 107284

thank you for your feedback with the PH function. That seams like a better way of controlling the PH. I didn't see it like that. as far as my pool i wont have a auto cover and will fight the battle all the time so we will see. i will be signing my contract in the nest week or two.

 

[jonpcar]

The funny (maybe not funny?) thing about the ORP system is that if you can "catch" the swings, and reset your setpoint before it overchlorinates (or you're left with zero FC causing an outbreak), it'll hold it's value for weeks / months and self-maintain.

To me, the biggest problem is that I want to "detect" the sudden swing so I can test / reset my baseline and adjust the ORP setpoint....

Now you've given me some hope. You see, that IS the kind of information that I can act on once I get my pool controller up and running (its design is based on an arduino-like device, Particle Photon). To detect those "swings" and notify that there is an issue would be be pretty straightforward. If only it were that simple...

Thanks, I hope you keep up the analysis as long as it still interests you, I will continue to watch.

 

[Bmwtown]

I agree with Jonpcar keep the info coming it really does help. There isn't much of that detailed info on the Intellichem and you are right in the middle of it.