Com link error between IC20 and Easytouch After Intelliph dispenses acid

We're writing over each other, ideas flyin' fast and furious. Check out post #36.
So this is how I'm seeing my options:
1. Put the Salt Cell on a separate relay/button from the filter pump. Put the acid pump on another separate button/relay. Start pump, start acid, stop acid, start cell. This would require me to free up 2 spaces, likely the light and the valve. Unfortunately I do have a nifty color light.
2. Put acid injection point downstream of salt cell and then I require 1 free space. Likely my actuated valve. Do I lose a lot not having acid going past the cell? Is it important for cleaning?
3. Extend ET4 to ET8 somehow, and then I can do whatever I want with no sacrifices.
4. Raspberry Pi. But I'm unfamiliar with it. Don't know where to start. Would that interact with the ET4 board?
 
This thread here is also an example of somebody implementing it on IntelliCenter. It also works for all models of EasyTouch, IntelliTouch, and SunTouch.

 
You do not need a relay to drive an actuated valve. The ET can drive two user defined actuators.
 
1. Put the Salt Cell on a separate relay/button from the filter pump. Put the acid pump on another separate button/relay. Start pump, start acid, stop acid, start cell. This would require me to free up 2 spaces, likely the light and the valve. Unfortunately I do have a nifty color light.
It sounds like you have a good grasp of your options. This first one would be somewhat complicated, but not too bad.

2. Put acid injection point downstream of salt cell and then I require 1 free space. Likely my actuated valve. Do I lose a lot not having acid going past the cell? Is it important for cleaning?
I don't actually know why Pentair recommends installing the injector before the IC, so I can't answer that one. Except to say most IC users don't have acid injection systems, so your IC won't be compromised in any way. It'll just work like everybody else's.

3. Extend ET4 to ET8 somehow, and then I can do whatever I want with no sacrifices.
I think this is the option you should explore first. It might actually be the simplest, cheapest one.

Here's the article. Look for the subhead "Convert an EasyTouch 4 to an EasyTouch 8." If that sounds beyond your skill set, let me know and we go to plan B.

 
SWCG must be wired through the Filter Pump relay.
Yes, but he could use a second relay to schedule on-off times separate from the filter pump relay on-off times. That's what I was suggesting, not that he switch from the filter pump relay to a different relay. It's how I'm running my IpH with an ET relay. The IC transformer (which ultimately powers the IpH pump) is still connected to my filter pump relay, but the acid pump is also routed through a second relay. The transformer powers on and off with the filter pump, but the acid injection only happens when the 2nd relay is scheduled. So even if the 2nd relay turns on, my IpH pump won't run unless the pool circuit is also on.

OP could do the same with his IC, and his IpH pump. It'd take three relays. One for the filter pump, which also powers the IpH/IC transformer, and then he could separately schedule his IC with the 2nd relay, and the IpH with the third. As I mentioned, it's a somewhat complicated solution, but doable if he really wants to go that way.

A version of what I'm describing is illustrated in my wiring diagram in my IpH hack thread:

 
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Why are you making this complicated. Just use a relay to power the acid pump. It does not matter if the IC is producing chlorine or not.
 
If this is true then it is the most simple. So why does the IPh turn off the cell before it doses?
Who knows. Some gimmick by Pentair. There are many many members with acid dosing pumps with SWCG's. Nothing is synced with the SWCG.
 
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Why are you making this complicated. Just use a relay to power the acid pump. It does not matter if the IC is producing chlorine or not.
I think that's exactly what @Flying Tivo does. I offered that idea a while back. I offered this more complicated solution as a way of more closely mimicking what the IpH does. Just expressing all the options. And do you really have to ask why I am making this complicated?! I'm Dirk, after all!! :ROFLMAO:
 
@JoyfulNoise, can you re-explain why you don't want to inject acid through an active IntelliChlor? And do you think it's a big deal or not?

It has to do with the electrochemistry going on at the plates. When you inject acid, the SWG volume is so low that you will definitely drop the pH very low, probably lower than 5 easily. By changing the pH of the electrolyte solution, you change not only it’s conductivity but also what chemicals species of chlorine are the most dominant. Low pH tends to favor the formation of chlorine gas over hypochlorous acid. That can interfere with how the chlorine dissolved into the water.

Also, when the plates are actively generating chlorine, the ruthenium metal surface is much more reactive to acid than when it’s passivated (in the off state). So you can more quickly degrade the plate surface.

It’s just best to avoid generating chlorine and injecting acid at the same time. One way to get around that is to put the acid injector AFTER the SWG in the return line. That way you are assured that you’re not sending a slug of acidified water into the SWG. You also want to be careful with acid injectors near heaters. If for some accidental reason the acid dosing injector were to leak acid into a stagnant water line, the pH at the heater could drop dangerously low and cause corrosion similar to how puck feeders always have check valves to make sure that acidic water doesn’t creep back into the heater manifold.

Anytime you can inject acid far away from sensitive equipment, the better.
 
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It has to do with the electrochemistry going on at the plates. When you inject acid, the SWG volume is so low that you will definitely drop the pH very low, probably lower than 5 easily. By changing the pH of the electrolyte solution, you change not only it’s conductivity but also what chemicals species of chlorine are the most dominant. Low pH tends to favor the formation of chlorine gas over hypochlorous acid. That can interfere with how the chlorine dissolved into the water.

Also, when the plates are actively generating chlorine, the ruthenium metal surface is much more reactive to acid than when it’s passivated (in the off state). So you can more quickly degrade the plate surface.

It’s just best to avoid generating chlorine and injecting acid at the same time. One way to get around that is to put the acid injector AFTER the SWG in the return line. That way you are assured that you’re not sending a slug of acidified water into the SWG. You also want to be careful with acid injectors near heaters. If for some accidental reason the acid dosing injector were to leak acid into a stagnant water line, the pH at the heater could drop dangerously low and cause corrosion similar to how puck feeders always have check valves to make sure that acidic water doesn’t creep back into the heater manifold.

Anytime you can inject acid far away from sensitive equipment, the better.
So why inject upstream of the SWCG at all? Does it help wash the cell?
 
What rate does the Stenner pump put the dilute acid into the line? At 20 gpm, you have 2 ft/s velocity in 2"pipe. I cannot imagine the acid is not dramatically diluted in that flow stream based on how fast the Stenner can pump the fluid into the line.
 

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