Intellichem ORP levels

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samendolaro

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Aug 29, 2012
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I had an Intellichem installed in December . It is an Acid Pump and it is controlling the Pentair Intellichlor through an easytouch 8. Everything seemed to work fine for the first 6 weeks, the PH and ORP were stable and predictable. But then the ORP readings started to fluctuate willdly sometimes dripping instantly from 700 to 300 and then some days climbing over 700 (the set threshold) and continuing to climb near 900 over several days even throught the chlorinator was not active .

I have a screenlogic system so I was able to capture the weekly changes , I can't attache them since they are about 300k so I attached one of the screenshots of what is happening.

The orp just fell off a cliff at about 1:30 and you can see how smooth the ORP reading were before that anf thats how it was for 6 weeks. I don't get alot of these large drops now but I do get that very erratic reading of the ORP

I put in a trouble-ticket with Pentair, they sent someone out who basically checked the sensors (Like i did by pushing a button) and they say they don't see anything wrong. I shared the ORP history with them and asked them if they consider that normal operation and they said "It doesn't matter what we think"


Has anyone else seen this ? Before I start pushing harder on Pentair I want to make sure this isn't normal.

Thanks

Scott

( I can send the PDF's of the history in full for anyone who wants to see them)
 

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This kind of thing is a large part of why we do not recommend ORP based systems. ORP wanders around for a variety of reasons, several of which have nothing to do with sanitation. Usually the changes aren't quite as dramatic as what you describe. Possible causes include a pool cover going on/off, a particularly bright sunny day, lots of people getting into the pool at once, a wide variety of possible chemical additions, and so on.

What is your CYA level? You normally only see variations in ORP that large when CYA is way too low.

Also, your PH is also varying quite a bit. That should not be happening and can throw off the ORP readings. You should check to see if it is tracking the actual PH, or is just wildly wrong. If it is tracking the actual PH, your other levels must be way out of balance. If you post a complete set of water test results we can advise about that. If it isn't tracking actual PH at least within at least +-0.2 it is broken. PH tracking should correspond to test kit results, while ORP readings tend not to.
 
Actually the CYA was near 0 at that time and that drop in PH (between 5pm and 6pm) was when I added CYA to see if that was the issue . I put the CYA back up to 40 but I still get the same reactions .

Overall the PH is pretty stable. No one has been in the pool, no covers, no operational changes. FOr 6 weeks the ORP and PH worked "Normal" then from 2/8 on it acts like what you see above. Some days I get those drops and others I get a continuous rise in oRP with.

This is a look at the week prior to this and how the ORP typically operated

Slide5.JPG
 
Might be a grounding issue. Check the grounds on the sensors and the unit the sensors connect to. Also check the connections of the sensors to the unit. Pull the sensors and check that they are clean.
 
One problem I see is that PH is not sufficiently stabilized. You have PH varying by at least 0.3, which is too much for reliable ORP control. Actually, I can't think of anything off hand that would cause that much PH variation in that short a period of time, unless your TA is really really low.

Second, if I am reading that chart correctly, the SWG barely came on at all on Monday through Friday. Is this an indoor pool? An outdoor pool should be losing a noticeable amount of chlorine each day, which is not reflected in that chart.

The only part of that chart that really makes sense is Saturday, which follows the kind of pattern I am familiar with.
 
That is an outdoor pool

What you saw with the SWG not coming on is exactly one of the problems I brought up. I will have 5 days where the orp readings are stuck in the 500-600 range then one day it will turn on in the 750 range and climb for 5-6 days then drop again.

As far as the PH goes. every time it rains here My PH will drop hard .

On that last chart the Pentair people were there on Friday and they took these readings from the pool ( CHLORINE 5.0, PH 7.6, ALK 80, STABLIZER 40 AND SALT 3300)

the chlorine should have never gotten that high so I'm thinking it is a bad sensor. I just got off the phone with another pentair tech and I am going to try some tests with tap water this weekend just putting the sensor in the tap water and seeing if it fluctuates or reads it correct.
 
Hum, several strange things going on then.

Regardless of what else might be going on, you will never get it to work unless you can stabilize the PH. That is simply way too large a PH variation for ORP based control to ever work. If you don't have a way to fix that, there is no point in even looking into the other issues.

Overall, your issues are stranger than usual, but this general kind of problem is exceedingly common. As I mentioned earlier, we do not recommend using ORP based control because of how common this kind of problem is. Simple percentage based control of your SWG is far more reliable.
 
Did some test over the weekend . Put the ORP sensor in filtered water (I use commercial filters ) tested the water ahead of time and no chlorine at all.

The pool reading at the time had a Chlorine level of 5 and was reading 642 on the ORP, the filtered water read 672 in one test and 705 in another (same water same glass) Waiting to hear back from pentair but I guess my sensor is hosed
 

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I have been using intellichem for a couple of years and it is both an art and science. I find it is most reliable when as many factors as possible are stable.
I have low but continuous flow in my pool.
I try to keep cya about 30-40 but no more.
I maintain recommended TA, but also use borates as a second buffer which helps to keep my PH very stable.
I dilute my muriatic acid feed 1/4 an have short feed and mixing intervals.
I maintain temperature at 88, but stable temp is more important than the actual temperature. Note though that when the weather gets cold in the fall all the readings become unreliable.
When probes go wacky do clean them as directed. I had a similar issue once and the probe cable was bad.
Update to the latest screenlogic and brick software if you haven't done so already and make sure your intellichem has the most recent firmware.

Hope this helps.
 
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