Pool Automation Controller


New member
To wrap up the conversation above, the key components of the BAS include:
1. The ability to power the pi with a 24vac or dc power supply. These power supplies are required for other equipment.
2. 10k temperature sensors
3. Dry contact sensors for flow switches
4. RS485 pass thru

When it comes to the BAS and all its capabilities, there is no need for PWM input or output and if that was replaced with 4-20ma then perhaps flow sensors could be accommodated. There are a number of low cost flow sensors out there but I don't know their reliability. They would make the most sense on a fill line and not part of the 2+ inch pool plumbing.

When you stack an 8 relay on the pi you now have the ability to switch up to 8 circuits on a single body system or 2 valves and 6 circuits on a shared body system. Keep in mind you cannot effectively operate a valve actuator without NO-COM-NC contacts. I am not an EE but most of the mofset implementations that I have seen have been SPST circuits.

It would be great to get a carrier for Atlas chemistry automation. One that doesn't have the goofball 40-pin pass thru connector on it.


New member
I would suggest using triac switched 24VAC circuits for both valve actuators (need 2 per valve) and for any 120/240 Volt switched loads. Then builders could use standard (and UL listed) relays for the line voltage switching (eg Omron G7L series).

For the valve actuators, I would recommend a pair of triacs to switch the 24V power and a discrete single-transistor inverter that ensures only one triac will be on at a time. Some care will be needed with the power budget -- the Valve actuators draw 3/4 amp (18W) when running.

A current sense on the valve control outputs would also be useful, that way the control software would be able to tell when a valve has reached it's position.


New member
Seems to me the laundry list of requests here is unlikely to fit on a single board. I think it might be most helpful if we prioritized what we want, in order from "most needed" to "least needed".

Here's my best stab at it, trying to be practical.

Step 1 - Single Body / No features / No Chem Monitoring
  • 24VAC/DC Power input
  • Isolated RS-485
  • 2x relays (Fireman's switch and Pump/Chlorinator). Single Throw. Normally Open. One of the two should have enough protection to drive an external 3HP pump relay.
  • 2x 10k Thermistor Input
  • 1x 0-10v Input (Filter Pressure)
Step 2 - Chem Monitoring - V1
  • Don't try to replace the Atlas Scientific White Box at this point
  • Add One contact closure input for a flow-cell flow switch
Step 3 - 2nd Body
  • Add another 10k Thermistor input
  • Add 2x more relays for valves. These should be double throw with both NO/NC contacts.
  • Optionally, put the relays on JST-XH connectors as described here, and prewire to a 24vac input per the wiring diagram.
Step 4 - Chem Monitoring - V2
  • Now actually try to replace the Atlas Scientific Whitebox.
    • 2x Isolated EZO circuits (ph and ORP)
    • 1x Non Isolated EZO circuit (RTD)
  • If possible an isolated i2c header that's compatible with the EZO-HUM (can replace the added 10k Thermistor I suggested with the 2nd body)
Step 5 - Bonus
  • Additional relays for more valves (Should this maybe come before Step 4? The whitebox works well).
  • 1x or 2x 4-20mA inputs (I guess? Seems lowest priority to me)
Final Idea - Upgraded Fan Module
  • Pool controllers are, by definition, mounted outside. I put the Sequent fan board on my stack. I don't think there's any way to fit it on the Pool Automation board. But I think there are some upgrades that could be made that would be awesome, not just for pool controllers, but all.
    • Add a header for an external fan (or two!).
    • Stick a 10k input (or two!) on there for monitoring enclosure temperature.
Looking at my stack, steps 1-3 seem like they should be achievable
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New member
My $0.02
I don't think you need any digital outputs.

I think relays could ALL be off-board. You have those great 8/16 relay daughter cards already that can easily be added on. I didn't know what a triac was but it sounds like you could feed a real relay from one and they probably take up less board space. I'm of the opinion that switching high voltage(120VAC+) should be done away from the Raspberry Pi. My NO switches are 2 lights (pool/spa), pool cleaner, SPA blower, and heater control(LV) and they all hang off Automation Direct relays built for HV. Triacs would be a nice way to trigger them. The automation direct relays I use require 13mA @ 24VAC to fire. There's just no way I'd power anything high voltage directly from a Raspberry Pi daughter card for a number of reasons.

24v *AC*/DC power input. This way we can share 24VAC with the valves and power the Raspberry Pi. I do this with my megabas today and it works great.
RS-485. Comms to control pool pumps, heaters, etc

Inputs... Here's where the answer is "It depends"
2 4-20mA. Some flow meters, pH meters(IXIAN), hall effect current monitors use these
4 0-10V. Pressure transducers, hall effect current sensors
4 10k Thermistor. Measuring temps
4 Dry contact sensors. Flow counters, flow switches (I think you'd want 2 for flow switches alone for safety)

Ideally, something universal selectable with jumpers (I think the MegaBAS does this today) would be even cooler so people could adapt the system to their unique needs and maybe you could get by with 10 pins instead of 14

Bonus: Atlas Scientific carrier would be awesome! (EC, pH, and ORP are the ones I'd use)
2-4(or more!) SPDT 24VAC Triacs supporting 750mA to drive actuators directly sounds incredible but sounds like SPDT triacs are not a thing?

Like Katodude said the MegaBAS was almost there.


New member
So, as I am building my latest version of my pool controller, I have discovered a few items. @cmc0619 is mostly right.

Currently it is based on a MegaBAS and an 8 relay board and an Atlas carrier board.

So turns out I am using the 0-10v output. I need 5v to power the pressure transducer.
A 1-wire connector would also be good (not Modbus). Just make it easier to wire up a standard 1-wire. If you can build in the resistor required that would also be good.
The Atlas carrier is icing on the cake, it would be nice to have that built in.


New member
Please help me to understand, I need Pneumatic Valves, I read a lot of information on the forums, but I can't decide which one to choose, some advise to choose pneumatic Valves, others advise to contact professionals, what do you think, how to be in this situation


New member
Great points all.

A few additional observations:

After a few months in operation using Analog output pressure sensors, I replaced them all with I2C. The analogs were way too sensitive to the environment, noise, temp etc. Gamico transducers are $38/ and worked beautifully. And i don't have to deal with calibration anymore.

I second the idea of monitoring contactors with digital inputs (as many as relays). I melted a jacuzzi heater because a mishap.

Most valves are still 24VAC 3-wire. To open close, you need a NO/NC relay/mosfet.

An MQTT type (or similar) to talk to Home Assistant or UDI is a must


New member
Im curious as well.
I have built this over the last month with the BAS and the 8 no/nc relays.
That was perfect until I got a new VS pump which isn’t rs-485 controllable but has an interface that outputs 5v and you use 3 relays to close that to one of 3 settings for different speeds. I had ordered a new 8 relay hat and the 16 relay (only NO) hat was shipped instead. All good and I could use it but I can’t for the life of me get it to work properly under the BAS.

One product would be a killer for the big 3 pool vendors as their markup is astronomical.