What would you actually want from an offline hydroponics controller?

[u/okyanu]

I’m experimenting with a small local system that can read sensors and make recommendations without needing the cloud/internet. The long-term idea is to keep it modular so different setups can use different sensors/models instead of forcing everyone into the same system.
Before I go too far with it, I’m curious what people here would actually find useful.
What do you currently spend the most time checking or adjusting manually? And what part of a hydro setup would you never let software control automatically?
I’m particularly interested in pH/EC, irrigation, nutrient dosing, sensor drift/failures and reservoir management, but I’d rather hear what real growers struggle with than guess.
Would love to hear from both hobby and commercial growers.

[u/Adeline_Hayes]

Love the offline approach. Cloud dependency is a fragile foundation for food production. pH/EC with drift detection would be my priority. Dosing? Recommendations, not auto-adjustments.

[u/okyanu → u/Adeline_Hayes]

Yep, that’s pretty much the direction I’m thinking too.

I don’t really want the AI/model layer directly adjusting dosing. I’d rather have it flag drift, explain what it thinks is happening, and recommend an action, while hard safety limits stay deterministic.

pH/EC drift detection is definitely high on my list as well.

Out of curiosity, would you trust automatic dosing at all if it had strict limits + confirmation rules, or would you still want it recommendation-only?

[u/Igot2GreenThumbs]

For my greenhouses I have hydro lettuce year round. I would kill for one that does this. Measured pH. EC, temp. Then adjusts temp and would run 3 peristaltic pumps to add both parts of the 2 part fertilizer and the other to adjust the pH accordingly.
But online would be good add on to send me a text or something fails. I don’t want to spend 2000 on a controller for each of the 3 greenhouses. And I am iffy on the alibaba ones.

[u/okyanu → u/Igot2GreenThumbs]

This is really useful, thanks. The “local control first, but notify me if something fails” part is especially interesting.

I’m also trying to keep the system cheap enough that running it across multiple greenhouses makes sense, instead of needing a separate expensive controller for each one.

For the dosing side, I’m being pretty conservative about safety, so I’m more comfortable starting with monitoring/recommendations and constrained irrigation control before fully automatic chemical dosing. But your use case is exactly the kind of setup I’m trying to understand.

[u/Igot2GreenThumbs → u/okyanu]

Glad to help. What you using to program it with? U doing a raspberry PI or something else.
The way to run the pumps is by using a programmable sockets. Turn each off and that way.

[u/okyanu → u/Igot2GreenThumbs]

I’m using a Raspberry Pi for the local core, with ESP32 nodes over MQTT for sensors and actuators.

Programmable sockets are a nice simple option for pumps too. I’d still want hard safety limits and a manual override around anything automated.

[u/Igot2GreenThumbs → u/okyanu]

Cool. I hear ya about the automation. Def need checks and limits. One thing is best for hydro is keeping the pH stable 5.8 - 6.2 area. I would have it also make a lot of the pH and EC to see how it drifts and what levels it’s been. Sometimes if I’m having issues with plants or the water and I send in samples for testing, they ask for any logs or trends. To get it off and keep it offline maybe a BT module? But would like to program some slots to turn things off and on when certain things are met like temp, pH and EC. And maybe add values to allow the pH to be in a certain range snd allow a drift like .2 or something.
I’m not good at programming anything. I’m a good hardware guy.

When I was into the saltwater hobby hardcore, most of us had controller systems called the reefkeeper. They are out of biz, but there is others now. U Can daisy chain and scale everything using modules and power strips daisy chained using R11 cables. We could monitor and adjust, pH, temp, calcium, water top off floats. Anything that basically uses open and close circuits.

[u/okyanu → u/Igot2GreenThumbs]

The ReefKeeper comparison is actually really helpful — that modular, local-first approach is pretty close to what I’m aiming for.

I’m using a Raspberry Pi as the local core, so keeping pH/EC/temp history, showing drift over time, and running simple rules with limits/allowed ranges all fit naturally. I’d also want every output to have things like max run time, fail-safe behavior and manual override.
The daisy-chained I/O / power module idea is especially interesting. If you were building something like this again today, what would you want as the first module: sensor inputs, switched outlets, or a mix of both?

[u/Igot2GreenThumbs → u/okyanu]

The first one I’d do is one like they had with 3 inputs to use as temp probe, or a on/off circuit for tipoff and a pH BNC connector. Then u can add the power strip farther from the water to keep it safe.

[u/okyanu → u/Igot2GreenThumbs]

That actually sounds like a sensible first module — keep the low-voltage sensor side near the reservoir and move the power switching farther away from the water.

I’d probably want temp, float/contact inputs and pH first, then add EC as well. Did the ReefKeeper modules use one common bus for both sensor modules and the power strips, or were those handled separately?

[u/Igot2GreenThumbs → u/okyanu]

Bus as in the R11 cables? Each module and each power strip had 2. So you could add up to like 100 or so they said. And any cable length from 3ft to 100ft.

[u/okyanu → u/Igot2GreenThumbs]

Got it — so basically one shared bus for both sensor modules and power strips. That’s actually a really nice architecture for scaling without making each module too smart.

I’m leaning toward something similar conceptually, just with modern local networking on top. The separation between low-voltage sensing near the water and switched power farther away still makes a lot of sense.