I really didn’t like using a fountain pump for a laser water supply. I’ve had too many fail in water fountains to trust one to a CO2 laser. I had some diaphragm pumps left from another project. They are the type normally used for RV sinks or marine wash down.
Some had a pressure switch so I chose one that didn’t. After all the goal here is flow not pressure. I used a 24V pump but only run it on 12V….
I added a flow sensor and a simple PIC microcontroller to shut the laser if the flow stops for any reason
Nice part is I cant even test fire the laser until the pump is running.
And I added a filter to keep the water clean.