Also called an in line duct fan. I have the six inch with a speed control that was advertised with it for that watt range. At full hilt it is way more than you need, but turned down it goes very slow. I usually tune at about 1inch WC. Quite quiet mounted on the underside of my table. Had it rigged with a U shaped tube back in the nineties when I first got it for suck and blow. Pitched the tube within a few weeks. Never used it. You want to see the reed you are working on, and for that you only need the draw side. I originally used a Magnehelic Gage to test starting pressure, but eventually switched to a hand held electronic thing I got from a place that sells test equipment to people checking A/C systems and related industries. Nice digital read out, easy to hook up to anything .
A Digital Manometer presumably. I've been thinking about getting one, so I guess your endorsement will trip the indecision!
One thing I've noticed is that room resonances and the resonances of your set up can easily influence the pressure reeds start at. I have difficulties around 50cents flat to 50 cents sharp of my G'' (G5). I remember a story about a concert hall just built that had a resonance at some note and when a dinger tried to sing it, nothing would come out. I had a much bigger blower set up on a big pipe ot another room ( too loud ) but the pipe had too many resonances and caused trouble. Mostly used it to try to get the maximum pressure a person would put on a reed. In this case, smaller was better. I use the big one to blow fumes from leather dyeing out of my shop now.
It would be interesting to get to the bottom of that - to determine fr example whether it's a Helmholtz resonance (ie a volume-related thing) or a standing wave (length related). I wonder if this ever surfaces in concertinas, or only on the test bed?
I had a reminder of how cancellations can occur in rooms recently. I'd just finished building a pair of loudspeaker boxes for our family room, plonked them in place and thought to run a quick frequency response check to make sure all was well. Rather than do the right thing, which was to test one at a time, I tested them both together. Because there was a sofa taking up the middle of the room, I put the mic stand at one end of it. Ran the test, and was appalled to see a massive cancellation in the middle of the spectrum. Smelling a rat, I moved the sofa, ran out a measuring tape and put the mic equidistant from the two speakers. Cancellation promptly disappears.
Interestingly, we suffer these cancellations any time we listen to stereo, but our brains seem quite happy to disregard them. Drives measuring systems nuts.