Semi-automatic nutes change equipment/setup

I’m (re-)building my system, and am going to build a plumbing system with electrically operated valves and an external pump so that I can flip some switches and drain; flip some switches and mix the resv (isolating plants until the nutes are ph’ed etc); then flip some switches and be back to normal.

I got sick of re-plumbing everything when I needed to drain, mix, fill.

Has anyone done this? Anyone interested in it?

I plan to increase the automation via Arduino … but this was easier to get started.


The valves 1 - 4 are controlled by DPST momentary toggle switches, and the pump will have a panel-mounted on/off switch as well. I have a 3" drain from the plants to the reservoir, and 3" electrically operated valves are … rather expensive. So that valve will be manual.

  • Drain: pump off, open 1 & 4, close 2 & 3, close manual 3" valve, pump on

  • Mix: pump off, close 1, 3 & 4, open 2. Keep 3" valve closed. pump on.

  • Normal: pump off; open 3, close 1, 2, 4. Open 3" valve. Pump on.


I know there are some people around here who have experience in instrumentation and those with plumbing backgrounds but not off the top of my head.

How big is the drain pan and reservoir?

Where does your drain go is that a holding tank the circle?

The drain is a sink. The reservoir is either 13 or 27gal, each of the four grow containers is 13gal. The drain from the plants is 1/2" and the reservoir is 3/4". Everything else is 3/4".

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Definitely go 27 gallons.

I’m sure your capable.

This is why I like autopots, no run off to deal with

I’ll have plenty of volume … and an auto top-off, and automated pH control.

Mostly, was curious if anyone is interested in the trials and tribulations of implementing this. :slight_smile:

I’ll try to document here…

I did stuff like this earlier in my career, but using plc instead of arduino. I know that @merlin44 and @Joshmcginnis28 both work with plc’s too, but not sure beyond that.


I guess I understand the application of PLCs in general, but am curious why a PLC would be better/easier/cheaper than an arduino?

In any case, phase one is manual.

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It’s definitely not cheaper, but better on just about all fronts imaginable. Speed, application, component availability. This is basically industrial automation equipment. Arduino is currently diy tinker toy version of plc’s. The problem with plc’s is that software is all proprietary and different among each manufacturer. Arduino directive is low cost open source automation.

The arduino stuff is plenty good for what you’re doing. I just don’t mess with it.



I’m making good progress acquiring parts and cleaning/re-plumbing my setup after the previous grow. I’m going to have four electrically controlled (3-wire) 3/4" valves arranged as described in the drawing above.

I’ll have a control panel with the following features:

  • On/off switch for pump. No on/off indicator (or maybe an “off” indicator, want to keep LEDs off in general)
  • On/off switch for the rest of the panel
  • Open/Stop/Close switches (SPDT) for each of the four valves
  • Green light for each of the four valves when the valve isn’t moving
  • Red light for each of the four valves when the valve is moving

All bundled into a 12x8 waterproof box, using DIN rail components.


  • Prototype works! Need to implement it x4 in the control box.
  • Plumbing not started yet

Here’s the schematic:

and here’s the control panel layout:

I was thinking about rigging an LED so that a red light lights up when the power is not applied to the pump. I don’t want to have it lit up when the pump is running (because it’d run during dark periods).

Yep, I did this. Have all of the electrical components except 12ohm resistors (shipping delay, ugh). I should have this wired up & ready for plumbing this week.
Wiring is done, except for the wiring to the pump and the valves. Still need to do plumbing, but I have to wait for the 5x10’ tent I got a smoking deal on to arrive before doing the plumbing…

Here’s some current pictures…