Acid dispenser

aprillh

Well-known member
Aug 8, 2013
94
Houston, Tx
We are about to build a SWG pool. I just heard about an acid injector/dispenser that sounds like a great idea but I haven't heard from anyone with personal experience. Our PB uses Sense and Dispense from Hayward. Has anyone used an acid dispenser before? Are they reliable? Worth it?
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
The thing I do not like about the S&D is that is includes the ORP sensor to attempt to automation the SWG chlorine output. In reality, ORP sensors do not work well enough for this and you are better off just using the SWG in the % output mode. So, with the S&D you are paying money for a system that you will only use half of. I think it is cheaper to just by an independent acid dosing system that you either have setup on a timer OR one that has a pH sensor ONLY and it adds acid as needed.

I see one of these in my future, but not sure when I will be able to justify the costs.
 

Readyforapool

Well-known member
Sep 17, 2013
738
DFW metroplex
PB just installed ours a couple of weeks ago, it's a Pentair. It has been a bit of a challenge to get it set correctly but so far, pushing the more or less button sure beats dragging the bottles out there and pouring it in every other day. I can say, it has helped with the scaling on the dark finish. We are about to need to refill the tank so that should be quite a task, not really looking forward to that!
 

aprillh

Well-known member
Aug 8, 2013
94
Houston, Tx
Jblizzle, what does ORP mean? I would have thought an acid dispenser would measure pH and add acid as needed. Why would it try to regulate the SWG?

Ready, how much does the tank hold? Is that normal to have to refill it every 2 weeks?

I need to research this a bit more. I'm still on the fence.
 

jamcha02

Well-known member
Jul 10, 2013
307
I use the intellichem by pentair. I have a 4 gallon acid tank and a stennar pump that doses based on input from the ph probe in the intellichem.

A 4 gallon tank lasts approximately 1 month for a 30k gallon pebble finish pool with a SWG.

I test ph about once a month to see if I need to calibrate the ph probe. The ph has ALWAYS been spot on, no calibration adjustments required 6 months in.

I love it so much I wouldn't go without it
 

Readyforapool

Well-known member
Sep 17, 2013
738
DFW metroplex
Mine is also 4 gallons, they did not fill it completely when they installed it. That being said, prior to this I was having to add a quart and a half about every two days to keep my ph at 7.5. I'm still testing my ph everyday because we had some serious scaling issues due to high ph and extremely hard water in the pool with a very dark finish.
 

bdex

LifeTime Supporter
Jul 3, 2014
389
Peoria, IL
I have thought about adding one of these systems if we stay at out current house. But I am all manual right now. No timers ok controllers etc.


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jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
The sense & dispense comes with 2 sensors. One for pH and another for ORP (pseudo-chlorine). That is why I said you would only use half the capability you pay for.
 

SunnyOptimism

Well-known member
Jun 20, 2014
860
Tucson, AZ
Pentair sells the IntelliPH system which is probably the most any residential pool owner needs. It's basically an acid Stenner pump that operates on a simple duty-cycle dispensing method (% output = % of hour dispense time) much like their IntelliChlor SWG. It can be easily linked into the IntelliTouch automation panel and operated remotely. No need for ORP or pH probes which are overkill for residential pools.

Once you spend about about a week measuring pH and adjusting the % output, then you're basically all set. You may need to readjust the dispensing in a seasonal basis (winter versus summer) but that's about it

Stay away from the IntelliChem systems as they are pH and ORP probe based systems that are overkill.

FYI, ORP = Oxidation Reduction Potential. It measures the half cell voltage produced by a standard electrode (either SCE or Hydrogen) and attempts to equate that voltage to an FC level. The problem with ORP is that the probe voltage is highly sensitive to changes in pH, TA and TDS (proxy for salt level) and it is easily fouled with CH. Therefore the voltage reading can be quite unreliable over time without constant calibration and cleaning of the probes. The probes also have a finite lifetime which means one more "thing" on your pool to replace.


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jamcha02

Well-known member
Jul 10, 2013
307
Pentair sells the IntelliPH system which is probably the most any residential pool owner needs. It's basically an acid Stenner pump that operates on a simple duty-cycle dispensing method (% output = % of hour dispense time) much like their IntelliChlor SWG. It can be easily linked into the IntelliTouch automation panel and operated remotely. No need for ORP or pH probes which are overkill for residential pools.

Once you spend about about a week measuring pH and adjusting the % output, then you're basically all set. You may need to readjust the dispensing in a seasonal basis (winter versus summer) but that's about it

Stay away from the IntelliChem systems as they are pH and ORP probe based systems that are overkill.

FYI, ORP = Oxidation Reduction Potential. It measures the half cell voltage produced by a standard electrode (either SCE or Hydrogen) and attempts to equate that voltage to an FC level. The problem with ORP is that the probe voltage is highly sensitive to changes in pH, TA and TDS (proxy for salt level) and it is easily fouled with CH. Therefore the voltage reading can be quite unreliable over time without constant calibration and cleaning of the probes. The probes also have a finite lifetime which means one more "thing" on your pool to replace.


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I, and many others, would definitely disagree that the intellichem is overkill :cool:

As far as your comments on the ORP sensor, I have personally observed a couple pools running on liquid chlorine, where the intellichem works perfectly with a CYA level of 30-50. The only case where the intellichem is not ideal for ORP control, is with a salt cell, due to high TDS and CYA

The intellichem is rock solid for PH control - perhaps my favorite piece of equipment. My ph is steady at 7.5 all the time and I've never had to recalibrate the probe. Since I purchased my unit with the rest of my pool equipment, I have a 3 year warranty, which is also reassuring.
 

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SunnyOptimism

Well-known member
Jun 20, 2014
860
Tucson, AZ
I, and many others, would definitely disagree that the intellichem is overkill :cool:

As far as your comments on the ORP sensor, I have personally observed a couple pools running on liquid chlorine, where the intellichem works perfectly with a CYA level of 30-50. The only case where the intellichem is not ideal for ORP control, is with a salt cell, due to high TDS and CYA

The intellichem is rock solid for PH control - perhaps my favorite piece of equipment. My ph is steady at 7.5 all the time and I've never had to recalibrate the probe. Since I purchased my unit with the rest of my pool equipment, I have a 3 year warranty, which is also reassuring.

Considering AprilH is building an SWG pool, using an IntelliChem system would be ill advised because, as you state, ORP is not suitable for salt water pools.

AprilH,

Please read this article for a detailed explanation of ORP control -

http://www.health.nsw.gov.au/environment/factsheets/Pages/orp.aspx

Also, since you are building an SWG pool, I would only recommend you go with an IntelliPH or similar Hayward product. The high TDS of your pool water will make using pH and ORP probes a hassle. In general, pH probes should be calibrated against known pH standards and cleaned on a regular basis to ensure that they work properly. That alone adds to the overall maintenance burden of your pool which is something you should minimize.


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jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
But, why buy the Intellichem when you readily admit that the ORP half of the system will not work with a SWG pool? Why not buy just an acid dosing system that ONLY has the pH sensor? Or even just a timer based acid dosing system? I know there are standalone acid dosing systems with pH sensors ... my friend has one.

I am sure the acid portion of the Intellichem and the Hayward Sense & Dispense would work fine. But my complaint for both is the same ... why pay for an ORP sensor that I would not use with my SWG pool?
 

VinceL

LifeTime Supporter
Apr 28, 2012
263
Newton, NC
Our fiberglass pool was installed in September 2012. So, we are in our second full summer of pool use.

We have the Hayward Sense and Dispense and we have a SWCG. I don't rely on the ORP to control the SWCG. I keep the CYA around 40-45, TA around 70, and I do check the ORP value just to make sure it hasn't gotten way out of whack (like down into the 300's :(). The pH sensor controls the acid feed from a Stenner pump. At the beginning of this summer, I had to make a one time adjustment to the calibration of the pH sensor. It has been right on the money whenever I manually test the pH. I have never seen our pH lower than 7.4 or higher than 7.6. Overall, I am happy with the Sense & Dispense.

Our pool is relatively small at 13,700 gallons (plus a 500 gallon spa). I filled up the acid tank at the beginning of the summer (early May), and I just had to add some acid about 2 weeks ago.
 

SunnyOptimism

Well-known member
Jun 20, 2014
860
Tucson, AZ
My recommendation of only going with an IntelliPH system still stands. And I am not "spouting rhetoric". I have advanced degrees in materials science and engineering and I have over 16 years of chemical process control experience from working in the semiconductor/microelectronics fabrication industry. I can tell you from that experience that chemical process control equipment requires constant maintenance to keep it functioning properly. And if you think pool equipment suppliers use the same high-end equipment that semiconductor manufacturers use, you're kidding yourself.

Many who have posted their professed "love" of this type of stuff are only on their first or second pool season with the units. Give it 5 years and then report back on how many pH/ORP probes have had to be replaced and how much time and money has been wasted tracking down false signals and "ghosts" in the machine.

The point of your pool build should be to maximize it's ease of use while minimizing maintenance and recurring equipment expense. Most of these fancy control systems were originally designed for public, large bather-load pools as a way of making them easier to maintain, safer and better sanitized. Their use in a low bather-load, low volume, residential pools make little or no sense in justifying their installation costs and fixed maintenance costs. A simple chlorine supply system (Stenner or SWCG) and a simple acid supply system (human hand or proportional controlled acid pump) is more than enough to keep a pool well sanitized, properly balanced and simple to operate.

But hey, I guess that's just rhetoric or something....


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jamcha02

Well-known member
Jul 10, 2013
307
There are several posts proving successful and maintenance free implementations of intellichem in a residential pool, both with and without salt. These systems are purchased for under $1000.00 and easily installed/maintained by someone with adequete DIY skills.

Also, I would not say that the ORP function is completely useless. It still provides an ORP reading which will stay relatively steady and begin to drop should the chlorine level take a plunge. This provides a small amount of process control - such as alerting you that the salt cell is not generating chlorine.

I go through about 4 gallons of acid a month to maintain ph @ 7.5. The intellichem doses exactly what I need, when I need it - no adjustments. I also only have to handle acid once a month. Is it worth it? - I'd say so!:cool:
 
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SunnyOptimism

Well-known member
Jun 20, 2014
860
Tucson, AZ
From all that I have read on this forum and on other sites, ORP probes can only be operated in pools with a CYA below 40 or else the chlorine buffering effect of higher CYA levels adversely affects the ORP voltage. TFP recommends all SWG outdoor pools to have a CYA level no lower than 60ppm or else you burden the SWG cell with higher FC demand and this lowers the SWG cells operating lifetime (10,000 hrs/cell as-built, actual mileage will vary)

As well, pH and TA need to be maintained at proper levels or else you will again cause false ORP readings. Finally, dissolved hydrogen generated by a SWG can cause the ORP voltage to drop even though adequate FC levels are being generated by the salt cell.

So, with all of those established facts in mind, I'll let the OP form their own opinion as to whether or not spending an additional $1k + regular probe replacement expense (~ $180 for pH and $250 for ORP) is worth it.

PS - To the OP, try downloading and reading through the installation, setup and operating manual for the IntelliChem and see if that is something you really want to spend time digesting. Not doubting your intelligence or willingness to learn in any way, just asking the question of whether or not simplicity and ease of use are a factor in your decision.



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susa

Well-known member
Oct 31, 2010
610
Deep South
Simpool pH

SIMPOOL.jpg
 

SunnyOptimism

Well-known member
Jun 20, 2014
860
Tucson, AZ
AprilH,

Please read that link I put in Post #11 as it is a good primer on ORP and details a lot of the pool specific water chemistry issues using ORP to control FC. Also, if you search the TFP threads on Chemical Automation, you will find lots of discussions of the problems people have had with both the Hayward and Pentair chemical automation systems.

No system is ever perfect and all choices come with trade offs associated with them. After 16 years of engineering work, i am a huge proponent of the principle "keep it simple, stupid." Too much time is wasted in this world letting "the perfect" be the enemy of "the good."

Ultimately it's your decision and I think it's wonderful that you are leveraging the experience of TFP in your pool build. I only wish I had known about TFP prior to my pool build as I would have done some things differently.




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Leebo

Admin
TFP Expert
LifeTime Supporter
Jul 21, 2011
10,507
Eastern Ohio
Pool Size
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Surface
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Chlorine
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AprilH,

I'd like to start off by welcoming you to the forum. I really hope that you are able to find the answers that you are looking for. I'd like to request that we sit back for a second and review this thread, which is on it's way south. Few of the last 5 or 6 posts have fully addressed the member's question. Please review the thread once again from post 1 and let's try and get this thread back on track. :D

Lee
 

aprillh

Well-known member
Aug 8, 2013
94
Houston, Tx
Thank you to everyone who replied. I really appreciate your expertise. I feel like I'm trying to learn too much about something that is so intangible right now. We decided to hold off on the Sense and Dispense for now. I'm thinking we will live with the pool for a season and see how time-consuming regulating the pH and adding acid really is. I like the idea of a fully automated pool but as my dad used to say of all the bells and whistles - that's just one more thing to break.

If we do decide to get an acid dispenser in the future, it sounds like we just get one that only regulates pH instead ORP too? For a SWG pool, is there a highly recommended one?
 

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