ORP accuracy/reliability, worth investing or not?

[jpcolin]

Hello,

I'm still in the proces of choosing my pool automation, and i would like to automate as much as possible.
So i was thinking about pentair intellitouch and intellichem (with liquid chlorine dosing not SWG), but i read a lot of complains about ORP sensing (for chlorine regulation), not only from Pentair but other brands alslo, is it worth investing in this? Most stories i have read, they say that after a while struggeling they just disconect the ORP reading and do it manualy.
So what is your advice?

Thank you

 

[dschlic1]

ORP will work, but you must keep a very low level of CYA. No more than 20 ppm. Above that amount, ORP will not change in a reliable manner with respect to free Cl.

 

[jpcolin]

thanks for your answer, are there any downsides of keeping low CYA? and how do you achieve it?

 

[Bama Rambler]

The downside of trying to maintain a lower CYA level is that you use a lot more bleach maintaining proper FC. Especially if you live in a sunny climate.

Even with a lower CYA level you're not guaranteed that ORP will work reliably over time.

 

[jpcolin]

Ok, i heard about FC probes, do you know any system that has that?

 

[Bama Rambler]

I've read a little about the amperometric probes, but haven't seen any in service. They're supposed to be compatible with CYA. The downside is that they're pretty expensive.

I don't know of any pool automation systems that use them. There could be some that I haven't heard of.

 

[Patrick_B]

The industrial ones are very finicky on calibration I know that much. I agree with Bama, and I don't think the technology has made it down to pools yet, but I don't keep up with it either.

 

[Ahrand]

ORP kinda works if :
- CYA is under 20
- probes are recalibrated every year
- probe housing is keept clean (no debris)
- new probes every 3-5 years
- with pool closing: dismantled and stored in storage fluid over winter

 

[jpcolin]

ORP kinda works if :
- CYA is under 20
- probes are recalibrated every year
- probe housing is keept clean (no debris)
- new probes every 3-5 years
- with pool closing: dismantled and stored in storage fluid over winter

Well that would work for me! Can anyone confirm?

So Ahrand that your case, you're happy with it, i see you are from Belgium too?
I would love to have more info about your setup (Logo Siemens), i'm actualy looking to "make" my own automation too.

 

[Ahrand]

So Ahrand that your case, you're happy with it, i see you are from Belgium too?
I would love to have more info about your setup (Logo Siemens), i'm actualy looking to "make" my own automation too.

Actually, I switched it off after 3 seasons fighting with it...
At the top of summer you need more than 20CYA, otherwise the sun will burn more chlorine tegen the swcg can make.
I trust my Siemens automation more now.
Are you Dutch speaking ? Send me a private message.

 

[dradam]

I wrote an article in diy pool automation with Pentair. I have been happy with the coordination of their system. ORP probes as you know are an indirect way to monitor FC. These probes are finnicky. I run a very low flow 15 gpm 24/7 and try to keep my pool at a unifor temperature-- all automated. With that I find orp to be consistent. I have not yet seen cost effectve FC probes. Search the forum for DIY pentair Pool automation and you can find the article. hope it helps.