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Thread: Really confusing me though is the reference to ORP

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    Really confusing me though is the reference to ORP

    Quote Originally Posted by acaciolo
    Hey Garet,

    We have about 50 intellichems installed at our customers now, and they really love the fact that they don't have to test chlorine or pH. Orp absolutely fluctuates a little 10% or so each way....but it doesn't cause an issue. pH is also rock solid.

    Intelliph is basically a dumb pump that will pump a preset volume of acid into your pool, regardless of whether you need it or not.

    Intellichem uses probes to monitor the water and only dispense acid (and sanitizer) then the cells detect that there is a need.

    Also, I've been beta testing a new firmware version for pentair on the intellichem...and it really adds some amazing intelligence to make the unit even that much more hassle free!

    tony c
    monogram custom pools
    Tony,

    Thanks for the response. I must be missing something here. When I buy IntelliChem, do I also need to buy IntelliChlor and IntelliPh to get full functionality out of IntelliChem or does IntelliChem come with its own repositories to dispense chlorine and acid?

    What is really confusing me though is the reference to ORP. I have checked Pool School a few times and can't seem to find references to it.

    When I search google I get this.

    The above link seems to imply that ORP is the mechanism used to determine sanitizer (chlorination) levels. However this and other threads suggest the ORP testing in automation tools is not to be trusted. If ORP is trully for sanitation level checking and is not to be trusted, then how can this equipment be trusted?

    Please help me sort this out.

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    JasonLion's Avatar
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    Re: Really confusing me though is the reference to ORP

    The IntelliChem is a combo of sensors and controller. To get it to work you need to add an acid tank/pump and an IntelliChlor. The IntelliPH is a separate system that includes much simper controller that is time based instead of sensor based; it includes an acid tank and acid pump.

    ORP is a sensor technology that is somewhat correlated with the FC level most of the time. ORP stands for oxidation reduction potential. ORP readings change as FC levels change, but they also change based on some other things, which can't always be held constant in practice. ORP sensors have all kinds of problems, but with enough attention they can be used in some situations, especially commercial pools. The IntelliChem system includes both PH and ORP sensors. The IntelliPH includes neither PH nor ORP sensors.

    I strongly recommend against ORP based chlorine automation in outdoor residential pools. Sometimes, especially when used with a SWG, they do not work at all. And even when they do work they add complexity, additional failure modes, and cut the SWG lifetime in half, all without providing any obvious benefit.

    The standard way SWGs work, which is also the way the IntelliPH works, is to run some adjustable percentage of the time that the pump us running. You then adjust the percentage setting until your get the PH/FC levels you are looking for. This is a very simple and reliable system that works quite well for outdoor residential pools.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Really confusing me though is the reference to ORP

    Hey guys,

    looks like jason got all your answers.

    The only thing I disagree with (and this doesn't happen often) is the ability of ORP sensors to work on outdoor pools. I understand the issues with the theory of how orp works, but with practical first hand experience with well over 50 outdoor residential pools being controlled with ORP sensors (some as long as 7 years,) I can tell you from actual experience, at least on the pools we build, they work extremely well.

    In 7 years, I haven't had 1 issue with a chlorine level related to the orp sensor. I've had salt water cells not keep up because of low salt or low cya....and I had 1 orp sensor that was giving erroneous readings because the customer was using cyanauric acid to lower their pH! (yeah...that type of acid didn't work well for lowering pH.) CYA was over 100 and the orp readings were a mess.

    But we've found through our customer's pools that if the cya is kept between 40-50, the orp sensors really do a great job of keeping the chlorine level in check.

    note..we use salt water cells on all of our pools and the pools are only opened about 7 mos a year.

    tony c
    monogram custom pools
    Owner of Monogram Custom Pools in NE PA. My Personal Pool - 1000sf gunite pebble pool with 1500 gallon spa/grotto and 500 gallon outdoor spa; Pentair i9 Intellitouch with i10x expansion panel. Screenlogic 2/iPhone
    Intelloflo SVRS main pump, 6 whisperflow pumps 2hp to 3hp, Intellichem system, ic60 salt water cell, Sta rite 400k btu heater, Pentair 120k btu heat pump

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    JasonLion's Avatar
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    Re: Really confusing me though is the reference to ORP

    acaciolo, apart from your report, considering only ORP/SWG systems we have had eight or nine reports of ORP being totally unusable, and three or four of the FC level wandering around fairly dramatically but people finding that acceptable. Quite a few of the people having problems have gone to extreme lengths to try and get their systems to work, including replacing sensors, adjusting CYA levels, working with the equipment manufacturer, changing circulation patterns, etc. In no case was the FC level ever stable, nor would I expect it to be since ORP readings vary with all kinds of things, including the amount of sunlight currently hitting the pool.

    The only first hand reports of ORP actually working well have all been from people using chlorine/bleach pump systems.

    If you have some magic formula for getting ORP to work, please share. However, I suspect that if you actually measured the FC level from hour to hour you would find that it varies rather dramatically. That doesn't have to be a problem, if you don't mind the wasted call life, but stable it isn't going to be. Regardless, the secondary issues remain including the costs of regular sensor replacement, occasional sensor fouling, extra winterizing effort, reduction of cell life to approximately half of what it otherwise would be, and so on.

    The number of reports of problems with ORP far exceeds our standard for "trouble free usage", and the alternative of simple percentage based control is so reliable and problem free that there is really no point in even looking at anything else. Just to remind, all of this only applies to outdoor residential pools. Percentage based control is essentially useless in indoor pools, and commercial pools have varying bather loads, and thus varying chlorine demand, which make something better than percentage control very desirable.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    acaciolo's Avatar
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    Re: Really confusing me though is the reference to ORP

    Hey Jason,

    I don't doubt that we would have varying levels of FC in our pools (including my personal pool)...but I can tell you without exception, in my over 50 pools with swg and orp, we have never had any algae blooms...no cloudy water....nothing that caused any headaches.

    Is the chlorine up and down? probably. Is it text book accurate? probably not. Does it keep the pools algae free and sanitized? absolutely. So although there might be fluctuations, they aren't enough to have ever caused any problems.

    Regarding our system...we have been using Pentair SWG exclusively and have been using their intellichem's since they came out. Before that, I was using autopilot's total control system (but that doesnt' allow remote monitoring...so we switched to pentair.)

    We keep our CYA below 50, keep the salt at 3400, run the pump for 12 hours a day and inject the acid BEFORE the cell in order to keep it clean. My oldest system still has an 8 year old autopilot cell that shows no signs of scaling and is still running strong. The rest are pentair and the oldest is 5 years. No scaling...no maintenance. We've never even had to clean the cells.

    So...for true geeks like us, just knowing that the chlorine might be fluctuating up and down a little is tough to handle. But now that I am too busy to check my chlorine levels a few times a day...and since most of our customers don't want to do that either, I guess that fact that the systems have kept problems away for so long is all we needed to be satisfied.

    I 100% agree with your analysis, but I also can't ignore the fact that the orp/swg combination has worked perfectly for me for 8 years on our pools. But my definition of "perfect" is related to customer satisfaction and a sparkling pool. I don't disagree that the levels might fluctuate...but so far, that fluctuation hasn't caused us any issues.

    as usual, thanks for all the great insight!


    ps...I've had a few calls from forum member (just one this week about questions on the dolphin cleaner.) If anybody is ever having problems with orp systems, feel free to call me anytime to see if any of our setup parameters could work for you.
    tony caciolo
    monogram custom pools
    Owner of Monogram Custom Pools in NE PA. My Personal Pool - 1000sf gunite pebble pool with 1500 gallon spa/grotto and 500 gallon outdoor spa; Pentair i9 Intellitouch with i10x expansion panel. Screenlogic 2/iPhone
    Intelloflo SVRS main pump, 6 whisperflow pumps 2hp to 3hp, Intellichem system, ic60 salt water cell, Sta rite 400k btu heater, Pentair 120k btu heat pump

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    Re: Really confusing me though is the reference to ORP

    You guys are both right

    Using percentage based control of SWG runtime works better for outdoor pool FC management, but the intellichem can mimic this.
    ORP is not going to give fine graned FC control, but it is sufficient if you are simply trying to keep FC within a reasonable range.
    Some climates will require higher CYA levels than the intellichem system can accurately support, but most climates...especially when combined with a pool cover - should give good results with CYA around 50.
    ORP will likely require a larger cell than non-orp.
    Setting up and maintaining the intellichem takes extra time/effort and occasional additional costs for new probes/sensors/tubing that naturally wear out due to acid handling/etc. It may not fall into the "trouble free" category.
    On the other hand, general day to day management with the intellichem is significantly easier.
    24K gallon inground gunite/pebble sheen pool, 34'x16' 4-7.5ft deep, 750sq ft solar, pentair ultratemp, intelliflow vs+, ic60, intellichem w/ acid pump, quad de 100, intellibright 5g, intellitouch i5-3s with Screenlogic2, 3" primary piping - 2.5" at equip pad, auto switched deep heating and main returns, automatic safety cover w/ electronic lock and embedded recessed undertrack, sealed stamped concrete deck, dolphin deluxe 5, started up December 2011.

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    acaciolo's Avatar
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    Re: Really confusing me though is the reference to ORP

    thanks matt. I think you nailed it.

    one thing that it took me a while to realize when I started building pools 8 years ago...is that most pool owner's aren't like "us." They don't care if the FC is dead on....or if the ORP (which they don't even know what that is) varies. As long as the pool is clear, safe, feels good, doesnt' smell, and requires little work...is all they care about.

    Also, all of our customers have us open and close their pool. Part of our opening service is replacing the $17.00 pump head in the intellichem and replacing tubing if needed. (although my acid tubing is still going strong after 8 years!)

    just looked at your pool specs...looks like we built it! (although for ease of maintenance for the customers we use the sta rite system 3 500sf cartridge filter.)
    tony c
    monogram custom pools
    Owner of Monogram Custom Pools in NE PA. My Personal Pool - 1000sf gunite pebble pool with 1500 gallon spa/grotto and 500 gallon outdoor spa; Pentair i9 Intellitouch with i10x expansion panel. Screenlogic 2/iPhone
    Intelloflo SVRS main pump, 6 whisperflow pumps 2hp to 3hp, Intellichem system, ic60 salt water cell, Sta rite 400k btu heater, Pentair 120k btu heat pump

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    Re: Really confusing me though is the reference to ORP

    I've been using the Hayward Sense & Dispense system for a few years now, using ORP, and I have not had any issues. It did take a while to dial things in, but so far so good. My pool is clear and clean, chemical readings are on the money and chemical maintenance has been relatively easy.
    SW FL, 19K IG with spillover & cage, Goldline Pro-Logic PS-8, Hayward Sense & Dispense, Hayward Swim Clear 4025, Hayward Ecostar VS pump, Stenner MA pump, Aquabot, Hayward Aquarite SWG, Palin Pooltest 9, Helicol Solar.

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    Re: Really confusing me though is the reference to ORP

    Tony,

    I assume you use independent FC testing with a test kit and then set the ORP setpoint for that FC, correct? You don't just set the ORP to some absolute "standard" level, do you? Also, since you've got experience with many pools, do you find that the ORP to FC relationship is fairly consistent across such pools or does it vary (which is OK if you just use different ORP setpoints for each pool)? Do you use the same manufacturer of ORP sensors for all your pools?

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Really confusing me though is the reference to ORP

    Pentair supplies the ORP sensor normally.

    ORP is CYA level sensitive. Above 30, the indicative range of the FC in millivolts is significantly reduced because the CYA allows ORP too. This level will also cause cells to have more On time, reduce the meaningful information range for ORP, and potentially leave a pool with a very low FC value when the demands on it rise, such as when the Sun is high and there is a bather load. The ORP is not necessarily indicative of only the FC level.

    This is why proper testing is so important, as chem-geek alluded to.

    When a cell is being used, the IntelliPH, once dialed in, tends to keep the pH stable under normal conditions. If you added extra bathers, heat and sun, the pool might need more bleach to keep up the chlorine demand. This can cause the pH to rise meaning either dialing up the IntelliPH or manually adding a little extra.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    acaciolo's Avatar
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    Re: Really confusing me though is the reference to ORP

    Richard,
    Correct...we test FC test on each pool to get our target orp. 99.9% of the time it is between 3-5 fc at 650 orp. Some pools it is set at 675, some 625.
    We do use pentair's sensors on all pools (they claim they are "professional grade") and we have absolutely found that on our pools (cya the same on all...sun level almost the same..water temp the same) that fc and orp are very closely related and fairly consistent from pool to pool.

    Scott,
    that makes sense on orp in regards to cya and fc. We typically have been running the pools at a target of 40 and have seemed to have a happy medium.
    Owner of Monogram Custom Pools in NE PA. My Personal Pool - 1000sf gunite pebble pool with 1500 gallon spa/grotto and 500 gallon outdoor spa; Pentair i9 Intellitouch with i10x expansion panel. Screenlogic 2/iPhone
    Intelloflo SVRS main pump, 6 whisperflow pumps 2hp to 3hp, Intellichem system, ic60 salt water cell, Sta rite 400k btu heater, Pentair 120k btu heat pump

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    Re: Really confusing me though is the reference to ORP

    Here is an example of what I mean by Ben at POOLFYI, Pentair's pool and product support forum and trying to add other things to the site like some marketing and sales stuff, some industry news, cross links to Pentair marketing literature and manuals, etc..

    http://poolfyi.com/forum/topics/the-eff ... e=activity

    Jason hits a home run with this:

    orp-readings-vs-free-chlorine-readings-t32006.html#p273188

    chem-geek had this to say:

    ideal-orp-readings-t32046-20.html

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    MattM's Avatar
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    Re: Really confusing me though is the reference to ORP

    ORP doesn't mean not having to test FC manually daily and ph weekly. Anyone who isn't checking their FC manually at least 3-4 times week is asking for trouble, ORP or no ORP. But, if one configures the intellichem to run the SWG "by time" instead of "by slew" and uses a reasonable mimic of normal percentage swg config "50% on - so 20 minutes active/20 minutes wait cycle" and if one is diligent to choose an ORP set point modestly above the end of a desired FC range - than the risk of FC going low or high is relatively minimal as the SWG behavior will mostly be essentially identical to a non ORP config, except that it will run somewhat faster to recover lost FC and shutdown automatically if high FC point is reached. I'm taking daily FC readings and have a FC target of 7-10 with the last few days FC oscilating between 8.5-11.5 at CYA 50. Using the forced idle time to approximate SWG ontime settings also helps avoid ORP readings being forced low due to gas buildup.
    24K gallon inground gunite/pebble sheen pool, 34'x16' 4-7.5ft deep, 750sq ft solar, pentair ultratemp, intelliflow vs+, ic60, intellichem w/ acid pump, quad de 100, intellibright 5g, intellitouch i5-3s with Screenlogic2, 3" primary piping - 2.5" at equip pad, auto switched deep heating and main returns, automatic safety cover w/ electronic lock and embedded recessed undertrack, sealed stamped concrete deck, dolphin deluxe 5, started up December 2011.

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