Exciting , keep us posted. Do you have access to some type of measuring cylinder or cup? I use these https://www.amazon.com/dp/B01ECAQPWA/ , to calibrate / understand how much it doses for given pwm speed in given time period.Got some more stuff!!
This is what I have so far for my dosing pump build I will be working on the circuits tonight and should have the raspberry pi and proto hat tomorrow.
L293 chip https://www.amazon.com/gp/product/B01BADVVF8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
2 Peristaltic pumps https://www.amazon.com/gp/product/B0791YL351/ref=oh_aui_detailpage_o00_s02?ie=UTF8&psc=1
Buck converter https://www.amazon.com/gp/product/B06XRN7NFQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Raspberry pi 3 https://www.arrow.com/en/products/raspberrypi3/raspberry-pi-foundation
16gb sd card with noobs https://www.arrow.com/en/products/noobs-16gb-retail/raspberry-pi-foundation
Perma proto pi hat https://www.arrow.com/en/products/2310/adafruit-industries
I'm going to wait for a bit on the ph probe and hardware for that to see what progress @Ranjib makes on supporting @Roberto_b ph probe board. https://www.reef2reef.com/threads/reef-pi-ph-orp-adapter.478158/