Automation for pH control

[cpachris]

Only 3 weeks after the initial fill-up, but I can already tell that I will want to tackle some type of automation for pH control. Tired of handling acid every other day already. Can't even imagine how I'll feel in a year. Anyway, what I'm looking for is:

- advice/comments from those that have tried it. what did you try and how did you like it?
- thoughts on CO2 vs Acid feed vs Other?
- links to any good threads discussing the above

Edit by Jim R.

 

[tloomos]

I just installed a Hanna BL100 dosing pump for ph control this weekend. Too early to tell how good it will be, but I'm optimistic.

Here's a link to the pump I installed: pH Controller and Dosing Pump BL100 - Hanna Instruments

When I was researching, I saw a lot of recommendations for Stenner pumps. Ultimately I decided to go with the Hanna pump even though it's pretty expensive because I liked the sensor probe to control dosing. I got the version with the flow cell after talking to their sales team as it makes it a bit easier to perform maintenance and calibration on the sensor probe.

If you decide to get the Hanna pump, one thing to know in advance is that the kit includes 50mm (2") saddle tees. I needed 63mm (2.5") and it was a hassle to exchange them. If you need something other than 50mm and you contact them BEFORE you place an order, you might be able to get them to swap them out in the kit prior to shipping it out to you. Other than that, I found the equipment to be solid and well built and the kit really does have everything you need for installation, with the following exceptions:

1) I found the o-rings didn't work well on the nipples, so I used pipe thread compound instead to get a good seal
2) You will need an acid storage tank - I used a 5-gallon bucket from Lowes
3) The controller isn't supposed to be exposed to direct sunlight, so depending on your install location, you may need an enclosure or cover of some sort

Here's my installation:

 

[cpachris]

@tloomos I'm making a reminder now to check back with you in a month to see how you ended up liking/trusting it. Definitely interested in doing something like that. Any feel yet for how hands-off it's going to be? How long between acid additions for reservoir?

 

[tloomos]

So far, it's working out really well, but it's still very early. I'm in the "trust but verify" stage where I'm checking on it a few times a day to see what the reading is and make sure there are no error codes. Once I've seen it go up to 7.7 and return back down to 7.2 a couple times, I'll probably start really trusting it.

TFP recommends maintaining ph at 7.6-7.8 for my pool, but I've been happy with it a bit lower at 7.4-7.6. I have my pump configured to turn on with a hi target of 7.7 and hysteresis of 0.5 - so basically, it will turn on when the ph hits 7.7 and will run until it gets down to 7.2.

I have a fairly small pool, so lowering ph by 0.5 takes about 25oz of acid, and it usually takes maybe 3 days or so for the ph to work its way back up to 7.7. So if I figure 25oz every 3 days, and I start with 3 gallons in the tank, that covers me for about 45 days. I plan to check on it weekly when I do my pool maintenance, and when it has about a gallon left, I'll add more. Since I buy the acid in 2-gallon boxes, and I don't want to fill the tank too high, I figure 3 gallons is about where I'll be on a "full tank". Your pool looks to be twice the size of mine, but if you needed more or wanted to refill less frequently, you could always just get a bigger chemical storage tank. I took the cheap and easy route of using a 5 gallon bucket which I think will work well for me.

 

[cpachris]

Thanks for posting and will follow to see if the trust level grows and becomes as automated as you hope. Can I ask...does that controller let you maintain a tighter range if desired? Does the main filter pump need to be running or does the controller turn that on also?

 

[BDY]

Interesting setup - how are you venting the bucket with it being so close to the heater(?) and other things. Acid storage and venting is what’s stopped me from seriously considering a setup so far

 

[tloomos]

Thanks for posting and will follow to see if the trust level grows and becomes as automated as you hope. Can I ask...does that controller let you maintain a tighter range if desired? Does the main filter pump need to be running or does the controller turn that on also?

You can tighten the range as desired, it allows it to be 0.1 to 1.0. I have it at 0.5 only because that's the default. I was planning to let it run this way for a week, then tighten it up a bit. There is also another control option they call Proportional where the dosing is based on the difference between the ph and the setpoint and configured using a percentage. I didn't really look into this option much - it seemed confusing compared to the auto mode.

The main filter pump needs to be running. This ensures that the sensor is testing "current" water levels. In my setup with the flow cell, if the pump is not running, and the probe senses that acid is needed, it would start dosing, wouldn't detect a change in levels, so it would run until it hit the overtime timeout, which is 30 minutes in my setup. With the flow rate I have set (0.5 gph), that would dispense 32 oz of acid. As you can tell, there are a lot of settings they have to allow customization of how the pump will work to support various needs.

Interesting setup - how are you venting the bucket with it being so close to the heater(?) and other things. Acid storage and venting is what’s stopped me from seriously considering a setup so far

The venting is one of the things that I'm most concerned about and not sure how to get definitive guidance on it.

To be honest, I seldom use my heater, and the "heat" it outputs when running is on the opposite side, venting away from the area where the storage tank is. I created a small vent on the bucket, but not sure if it's enough and not sure how to determine that. It's using 1/2" PVC with 8 x 1/4" holes drilled in the top, and a 1" cap over it to keep water out.

 

[BDY]

Usually they say run a vent hose way away from the equipment space as the fumes are so corrosive

You might want to rethink that regardless of using the heater or not given the rest of the metal around it and the heater itself

Love the setup though - maybe you can run an exhaust line??

 

[tloomos]

That sounds like a good idea - Since I already have the lid ready for PVC connections, I could easily get an adapter and run a hose away from the equipment. How can I determine if the 1/2" PVC allows enough flow for proper venting?

 

[BDY]

I’m not an expert at that. My offhand idea would be that the normal venting is through the lid on the jug so a hose should be good? My second idea would be to pull HO the Intellichem or Intelliph specs and look at their vent size.

 

[Ahultin]

My intelliph vent is 1/4 hose run ~20ft away from anything susceptible to acid damage

 

[tloomos]

Thanks, that makes me feel far more comfortable with the 1/2" vent size. Based on this discussion, I'm considering whether I want to run a hose to vent away from everything or just move the bucket completely away and have a longer tube going from the bucket into the the dosing pump. The thing I liked about the current location is it's barricaded behind the plumbing and no chance anyone is going to bump into it or knock it over. The further I move it from the equipment, the less existing barrier I'll have, so I'd probably need to do something to protect it from kids, pets, ladders, whatever hazard may come its way.

 

[cpachris]

My intelliph vent is 1/4 hose run ~20ft away from anything susceptible to acid damage

@Ahultin are you happy with the intellipH setup? Been using it long?

 

[BDY]

I’d vote longer exhaust. Longer supply tube means greater chance of leak in hose

 

[MyAZPool]

@tloomos
I'll just throw a couple of things out here that you may want to consider for your current acid dosing setup. And although you are not running an IntellipH or Stenner setup, much of the same principles apply.

1. Venting: Venting is very important. Not just venting but venting away from your pool equipment pad and any other metal. I'll quote one of our resident IntellipH guru's (@Dirk), who explains it very well.
Why you should vent and how to vent: "The acid tank is supposed to be air tight. So as acid is drawn from the tank, you need air to be able to enter the tank to displace the acid leaving it. Same goes for temperature changes throughout the day and night: as the air in the tank heats and cools, the tank needs to breathe. And that air coming and going is provided by the vent. The problem with that is, as the tank expels air, it's also expelling acid fumes, and those fumes can chew up any metal in the vicinity of the tank. The corrosion often seen on those screws (ipH screws), is likely from acid fumes. But they won't stop there, those fumes can and will attack any other metal nearby, even stainless steel, like your other pool gear or your window frames or fence hardware, etc."

"Use 1/4" "acid-resistant tubing." Then you connect that tube to the IpH vent, and run it as far away from the IpH, your pad, and any other metal, as you can get. Try to slope it down from the IpH, and then turn the end of it down, too. It'll still pass air, but the idea is to allow any condensation to be able to drain out, and pointing the end down will keep it from filling with sprinkler water or rain."

2. Dilution: "Lastly, Pentair recommends diluting the acid in the tank. You can cut 31% acid in half, adding 1-to-1 water and acid. Or you can just buy the 14% acid. That helps minimize the corrosion and helps with the longevity of all the parts susceptible to acid. If you're running 31% (or higher) acid in the tank, that's asking for trouble."

Good luck with your new setup. It definitely looks promising.
r.
Oh yea, quick safety tip. If diluting, always add MA to water and NOT the other way around.

 

[Dirk]

Oh yea, quick safety tip. If diluting, always add MA to water and NOT the other way around.

Stuck with me from junior high chemistry class: "Acid inta wahtah, 'cause that's the way ya aughta."

@cpachris, the type of acid dosing system that might be best for you might be dependent on your existing (or planned) equipment (SWGs, automation controllers, timers, etc). If you could fill in your signature, you'll get better advice. Something like mine is ideal.

https://www.troublefreepool.com/account/signature

 

[Ahultin]

@Ahultin are you happy with the intellipH setup? Been using it long?

13 months and have been very happy with it HOWEVER , we are now experiencing what I beleive is the iph/intellichlor issue with the melted conductor. As of end last week the swg can no longer communicate with intellicenter or iph. Since it is still under the 3yr warranty I am pending a pentair service tech out to check.

 

[BDY]

I thought that issue was only IC60 if it’s IC40 that will cause me to rethink my future planning

 

[Ahultin]

I thought that issue was only IC60 if it’s IC40 that will cause me to rethink my future planning

From the wiki, it appears it's most ic60/iph combos and some ic40/iph combos

Pentair Intelliph - Further Reading

www.troublefreepool.com

 

[Dirk]

I thought that issue was only IC60 if it’s IC40 that will cause me to rethink my future planning

The failure can happen with either 40 or 60. That is confirmed. Pentair's warranty covers the failure. A very simple DIY wiring hack will prevent the issue but would void the warranty. Performing the hack on day # warranty-period-plus-one is a viable solution.

Of course, it's ridiculous to consider buying something that has a known issue you'll need to repair, but that is the current state of the Pentair offerings. I only suggest it because I am convinced the IC + IpH combo is a superior choice, for reasons I'll have to list some other time. Full disclosure: I've only owned the Pentair system, so don't actually have any direct experience with any other. But I know just enough about Stenner's offerings to make such a claim.

Regardless of which system you decide on, you won't regret automating acid dosing. It's a fantastic convenience and worth the money (IMO).