So I've been watching a listing on Amazon for years, the only affordable flow meter, but it was still around $100 to get everything I would need, which is why I didn't pull the trigger, and it was only in Liters.
Recently, I decided to look around again, and the same seller released a newer version that can toggle between gallons and liters, and included everything I needed: https://smile.amazon...0?ie=UTF8&psc=1
I received it yesterday, and just installed it tonight and did some testing/calibrating for the hall sensor.
So far, everything looks to be working well enough. I built it with john guest fittings to use the bev seal ultra tubing I use to go from the water filter to the HLT.
Here is the unassembled kit, and my fittings prepared:
Here it is assembled in place and attached to my water filter:
Here I'm calibrating the k value:
I got it to within about 1.5 ounces by weight for a gallon, so I felt pretty good about that.
Here is what the display looks like:
So the whole thing costs around $65, which to me was very reasonable. I am still thinking about replacing the solenoid with a stainless version with female NPT fittings to simplify the setup, but I'm not going to worry about that right now (though I may buy the solenoid soon).
The K value can be adjusted the .01 place, but the precision for actual volume didn't seem to reflect that resolution, so after I got it close, I didn't worry about it - I tried adjusting by .03 at a time, and didn't notice a significant difference in weight for a gallon reported by the meter.
My one nitpick is that the temperature sensor is threaded M8, and I couldn't find a simple way to get that to work with my 1/2" NPT fittings without drilling a coupling and tapping it M8 myself.
With my tests tonight, I'm pretty happy with it so far, and I'll definitely update later if anything fails or drastic changes in my experience. I did keep my water flow rate to .7 gallons per minute. I was tempted to see how it would handle a variety of flow rates with the k value, but I decided it wasn't worth the time, and my GAC 10 carbon filter is really only rated for 1 GPM anyway.
So if any of you are interested in a flow meter for your setups, I'd recommend you at least consider this one, as I think it is the only reasonable option at this price point. I haven't brewed with it yet though, so that will be the next test!