pH Probe Manifold Images and Ideas

[.jake]

I'm planning a two-phase pH project.
Phase 1 is the pH probe manifold. I'm planning to get the probe readings and I'll manually evaluate what it takes to drive the pH down. The reading will be processed with an Arduino or ESP. I'm good with the C/C++ code.

Phase 2 is to evaluate the reading and act with an acid feeder pump. I've already decoded and am reading the RS-485 bus so I can tell, among other things, if the pump is on or not, and what RPM it's at, so for phase 2 this will prevent feeding into an idle system.

So what I am looking for are images and ideas for probe manifolds. The probe I'm looking at can handle 100psi, so no issue there, but flow can be rough on the sensing element, so low flow would be ideal. I have drain plugs on the bottom of the pump basket and on the impeller housing. I assume the basket plug is vacuum but I don't know about the impeller housing plug. The pump is an IntelliFlo VS-3050. I was thinking about using one of the drain plugs on the pump body to tap for flow, but where to connect the other end is another point to work out. Maybe the aerator return line, but that would require a pressurized source tap and would make the fitting under the coping ooze effluent.

So let's see those manifolds and ideas on where to source and drain the effluent!

Thanks.

 

[kimkats]

WAY over my pay grade up am giving you a bump in case someone will be able to help.

Kim

 

[Bama Rambler]

Making the manifold is easy. Just use a threaded PVC tee and threaded to tubing fittings to run the tubing into and out of it.

As for making a slip stream. You can use the pump drain plug as the return, and pick a convenient place on the discharge side of the pump (after the filter would be good) and drill and tap a hole in the piping and use a threaded tubing adapter to plumb it into the system. I'd add a needle valve to regulate the flow past the pH probe.

If you have an unused tablet feeder, you could use one of it's taps to provide the inlet port.

 

[.jake]

Thanks for the bump kimkats, and thanks, Bama for your input. I agree the manifold isn't too much work, mostly wondered what others had done if they've tackled something similarly.

This member did it for other sampling reasons but the pics were spot photos, not big picture type.

I did a little testing on my pump. Indeed the two drain plugs are pressure and vacuum. Theoretically I could make the loop all in the pump housing. Though I dislike very much the idea of using the vacuum port in case of an air leak. Something else to think about.

I think the safest way to do it is to use the aerator discharge line. It's under pressure, I never use it, and it drains in to the pool. I could cut in a loop for the manifold.

This is what I have today and what I was thinking about below.

The other option would be to tap at the pump pressure port, pass it through the manifold and discharge it into a skimmer return line (the skimmers are venturi type and have water flow whenever the pump is on). The advantage is it returns below the water line, and I could use it (in phase 2) to deliver the acid, too. I agree with your suggestion about the valving down to moderate flow.

 

[Bama Rambler]

Either of the suggestions about where to insert the probe slip stream are good. I like the option of using the pressure port and return line (hopefully skimmer was a misnomer) to create the slip stream. As you said, that would allow you to inject the acid into the same port.

One thing I'd check is that the return line is lower pressure than the pump pressure port. It should be because it's after the filter, but it'd be wise to verify it.
Also, I'd make sure to install a check valve in the line before the injection point once you do that.

 

[.jake]

Maybe return line would be better, but it returns through the skimmer, and the valves are labeled skimmer so I just call it that. Here's what I mean. Only one of the two skimmers have suction line. The one I would tap is venturi only.

 

[Bama Rambler]

That's not very common, but since it's still a return line, it would work.